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Abstract:

A method for positioning and feeding media into a media feed path
according to one embodiment includes moving a first media sheet from the
top of a stack of media sheets in a media storage location in a media
process direction from an initial pick position into a media feed path
leaving a second media sheet at the top of the stack of media sheets. In
the media storage location, the second media sheet is moved opposite the
media process direction away from an entrance to the media feed path
until a leading edge of the second media sheet reaches a known
predetermined position in the media storage location. After the leading
edge of the second media sheet reaches the known predetermined position,
the second media sheet is moved in the media process direction from the
stack of media sheets into the media feed path.

Claims:

1. A method for positioning and feeding media into a media feed path,
comprising: moving a first media sheet from the top of a stack of media
sheets in a media storage location in a media process direction from an
initial pick position into a media feed path leaving a second media sheet
at the top of the stack of media sheets; in the media storage location,
moving the second media sheet opposite the media process direction away
from an entrance to the media feed path until a leading edge of the
second media sheet reaches a known predetermined position in the media
storage location; and after the leading edge of the second media sheet
reaches the known predetermined position, moving the second media sheet
in the media process direction from the stack of media sheets into the
media feed path.

2. The method of claim 1, further comprising if the second media sheet is
shingled fed with the first media sheet when the first media sheet is
moved from the stack of media sheets, separating the second media sheet
from the first media sheet by moving a leading edge of the first media
sheet tangentially over a separator roller downstream from the initial
pick position and rotating opposite the media process direction, wherein
a leading edge of the second media sheet strikes the separator roller in
a non-tangential direction stopping further motion of the shingled fed
second media sheet in the media process direction.

3. The method of claim 1, wherein moving the second media sheet opposite
the media process direction until the leading edge of the second media
sheet reaches the known predetermined position includes moving the second
media sheet opposite the media process direction until a trailing edge of
the second media sheet contacts a restraining member in the media storage
location opposite the entrance to the media feed path.

4. The method of claim 1, further comprising raising a lift plate
supporting the stack of media sheets as the second media sheet is moved
opposite the media process direction.

5. The method of claim 4, wherein the lift plate is raised in indexed
moves.

6. The method of claim 1, further comprising after a predetermined number
of media sheets are moved from the stack of media sheets into the media
feed path, raising a lift plate supporting the stack of media sheets.

7. A method for positioning and feeding media into a media feed path,
comprising: rotating a pick mechanism in a first direction to move a
first media sheet from the top of a stack of media sheets in a media
storage location in a media process direction from an initial pick
position into a media feed path leaving a second media sheet at the top
of the stack of media sheets; rotating the pick mechanism in a second
direction opposite the first direction to move the second media sheet
opposite the media process direction away from an entrance to the media
feed path until a leading edge of the second media sheet reaches a known
predetermined position in the media storage location; and after the
leading edge of the second media sheet reaches the known predetermined
position, rotating the pick mechanism in the first direction to move the
second media sheet in the media process direction from the stack of media
sheets into the media feed path.

8. The method of claim 7, further comprising moving a leading edge of the
first media sheet tangentially over a separator roller downstream from
the initial pick position and rotating in the second direction to
separate the second media sheet from the first media sheet if the second
media sheet is double fed with the first media sheet when the first media
sheet is moved from the stack of media sheets.

9. The method of claim 8, further comprising if the second media sheet is
shingled fed with the first media sheet when the first media sheet is
moved from the stack of media sheets, moving a leading edge of the second
media sheet against the separator roller in a non-tangential direction
stopping further motion of the second shingled media sheet in the media
process direction.

10. The method of claim 7, further comprising rotating the pick mechanism
in the second direction to move the second media sheet opposite the media
process direction until a trailing edge of the second media sheet
contacts a restraining member in the media storage location opposite the
entrance to the media feed path.

11. The method of claim 10, further comprising after the second media
sheet contacts the restraining member, continuing to rotate the pick
mechanism in the second direction while applying a normal force with the
pick mechanism on the second media sheet small enough to allow the pick
mechanism to slip against the surface of the second media sheet.

12. The method of claim 7, further comprising raising a lift plate
supporting the stack of media sheets when the pick mechanism is rotated
in the second direction.

13. The method of claim 12, further comprising holding the lift plate in
place when the pick mechanism is rotated in the first direction.

14. The method of claim 7, further comprising after a predetermined
number of media sheets are moved from the stack of media sheets into the
media feed path, raising a lift plate supporting the stack of media
sheets.

15. A method for positioning and feeding media into a media feed path,
comprising: rotating a pick mechanism in a first direction to move a
first media sheet from the top of a stack of media sheets in a media
storage location in a media process direction from an initial pick
position into a media feed path; moving a leading edge of the first media
sheet over a separator roller downstream from the initial pick position
and rotating in a second direction opposite the first direction to
separate a second media sheet from the first media sheet directly beneath
the first media sheet in the stack of media sheets if the second media
sheet is double fed with the first media sheet when the first media sheet
is moved from the stack of media sheets; rotating the pick mechanism in
the second direction to move the second media sheet along the top of the
stack of media sheets opposite the media process direction away from an
entrance to the media feed path until a trailing edge of the second media
sheet contacts a restraining member in the media storage location
adjacent to the stack of media sheets opposite the entrance to the media
feed path; and after the second media sheet contacts the restraining
member, rotating the pick mechanism in the first direction to move the
second media sheet from the stack of media sheets into the media feed
path.

16. The method of claim 15, further comprising after the second media
sheet contacts the restraining member, continuing to rotate the pick
mechanism in the second direction while applying a normal force with the
pick mechanism on the second media sheet small enough to allow the pick
mechanism to slip against the surface of the second media sheet.

17. The method of claim 15, further comprising raising a lift plate
supporting the stack of media sheets when the pick mechanism is rotated
in the second direction.

18. The method of claim 17, further comprising holding the lift plate in
place when the pick mechanism is rotated in the first direction.

19. The method of claim 15, further comprising after a predetermined
number of media sheets are moved from the stack of media sheets into the
media feed path, raising a lift plate supporting the stack of media
sheets.

20. The method of claim 15, further comprising if the second media sheet
is shingled fed with the first media sheet when the first media sheet is
moved from the stack of media sheets, moving a leading edge of the second
media sheet against the separator roller in a non-tangential direction
stopping further motion of the second shingled media sheet in the media
process direction.

Description:

CROSS REFERENCES TO RELATED APPLICATIONS

[0001] This patent application is related to the following United States
patent applications:

[0012] Each of the foregoing applications is assigned to the assignee of
the present application.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0013] None.

REFERENCE TO SEQUENTIAL LISTING, ETC.

[0014] None.

BACKGROUND

[0015] 1. Field of the Invention

[0016] The field relates generally to media input feed systems for an
image forming device ("IFD") having a removable input tray.

[0017] 2. Description of the Related Art

[0018] IFDs, such as printers, scanners and photocopiers utilize media
feed mechanisms for feeding various types of media sheets into the IFDs.
Examples of the various types of media sheets include, but are not
limited to, printing paper, bond paper, coated paper, fabrics,
transparencies and labels. Almost all of the media feed mechanisms
include a pick roller that feeds a media sheet into the IFD for further
processing. In a media feed mechanism, various arrangements of the pick
roller may exist for feeding the media sheet into the IFD.

[0019] In one such arrangement of a media feed mechanism, the pick roller
may be coupled with other components of the media feed mechanism to exert
a normal force on the media sheet. Examples of the other components that
may be coupled to the pick roller include solenoids, cams, pick arms,
gears, shafts, and the like. Simultaneously, the pick roller may be
rotated due to the coupling with the other components to push the media
sheet into the IFD due to friction between the pick roller and the media
sheet. Herein, pushing the media sheet into the IFD refers to pushing the
media sheet in a media process direction into a specific section of the
IFD, for example, pushing the media sheet into a `printing zone` where
the IFD is a printer.

[0020] In existing media feed mechanisms, the normal force, which is
applied substantially perpendicular to the flat surface of the media
sheet by the pick roller, is generally of a constant value for all types
of the media sheets. For example, the pick roller may exert a constant
normal force on a bond paper, as well as, a transparency. As is known,
media may have different densities, weights, thicknesses and stiffnesses.
Further, the normal force required to feed one type of media into the IFD
may be greater than the normal force required to feed another type of
media. Accordingly, due to the application of the constant normal force
on all types of the media sheets in existing media feed mechanisms,
multiple feeds or misfeeds of the media sheet may occur.

[0021] Further, over time the normal force exerted by the pick roller may
decrease due to wear of the pick roller. However, the existing media feed
mechanisms may not facilitate increasing the normal force exerted by the
pick roller on the media. This limitation may result in replacement of
the pick roller in the IFD.

[0022] Upon coming in contact with a media sheet, a pick roller applies a
normal force (referred to as `N`) on the media sheet. Further, there
exists a coefficient of friction μ between pick roller and the media
sheet. The rotation of the pick roller along with normal force and the
coefficient of friction μ result in a driving force in a direction,
such that, the media sheet is fed into the IFD. Normal force, the
coefficient of friction μ (referred to as `μ`) and driving force
(referred to as `D`) may be related by the following equation:

D=μ*N

[0023] As per the relation in the above equation, normal force N is
directly proportional to driving force D. It will be evident to a person
skilled in the art that a particular value of driving force D drives the
media sheet into the IFD. However, it is also evident from the above
equation that driving force D also depends upon the coefficient of
friction μ, and accordingly any variation in the coefficient of
friction μ may vary driving force D. The coefficient of friction
(μ) may differ for various types of the media sheet.

[0024] It will be evident to a person skilled in the art that based on the
relation provided above, the magnitude of normal force N may need to be
increased when the coefficient of friction (μ) between the media sheet
and a pick roller decreases, in order to maintain the particular value of
driving force D required to feed the media sheet in the media processing
device. Similarly, the magnitude of normal force N may need to be
decreased when the coefficient of friction μ between the media sheet
and a pick roller increases, to feed the media sheet in the media
processing device.

[0025] IFDs typically include multiple input sources to introduce the
media sheets into the media path. The input sources may accommodate a
range of media types and a range of media sheet quantities from a single
media sheet to large quantities such as 2,000 or more sheets. One type of
input source is referred to as a removable media input tray ("RMIT")
integrated within the same housing that contains the imaging units of the
IFD. A multi-purpose feeder may also be provided on the image forming
device housing or as part of the integrated media tray for accommodating
a low number of media sheets and often for specialty media sheets that
are difficult to feed through normal input trays, such as envelopes,
transparencies, and cardstock.

[0026] Another input source is referred to as an option assembly typically
comprising a housing and a removable media input tray that is slidably
received into the option housing. These option assemblies are typically
stackable allowing one or more option assemblies to be used with a single
image forming device which is typically positioned on top of the
uppermost option assembly in the option assembly stack. Typically each
option assembly may contain a different type of media such as letterhead
or a different size such as A4 or a larger quantity of the same media
type that is found in the integrated RMIT.

[0027] Each option assembly provides an extension to the media path of the
IFD and may provide one or more additional branches or avenues for
introducing media into the media path of the IFD. The media path
extension extends from the top to the bottom of each option assembly and
is upstream of the media path in the IFD. When another option assembly is
positioned below an option assembly, the media path extension permits
media in the lower option assembly to be fed through the upper option
assembly and into the media path of the IFD that extends at its upstream
end through the front portion of the integrated media tray. To accomplish
the feeding of media either from a RMIT in an option assembly or from
another option assembly, feed rollers have been provided in each option
housing above the media tray therein and in the media path extension to
receive picked media either from a lower option assembly RMIT or from its
own adjacent RMIT. One disadvantage of this arrangement is that the feed
rollers increase the overall height of each of the option assemblies by 2
cm or more. If a large number of option assemblies are stacked together,
this added height may raise the overall height of the image forming
system by 10 to 20 cm sometimes requiring a user to choose between
removing an option assembly and having to reach to obtain the output of
the imaging forming system. It would be advantageous to have a lower
height option assembly while still be able to provide for pass-thru media
feeding.

[0028] With the addition of one or more option assemblies to an IFD,
alignment of the media path extension between the various components and
to the media path in the IFD becomes problematic due to variations in
component tolerances, also known as "tolerance stackup." Misalignment of
the reference surfaces can cause damage to the leading edge of the media
or skewing of the media as it moves along the media path extensions and
into the IFD. To correct this, alignment reference surfaces against which
an edge of the media being fed have been provided in the media trays in
the option assemblies. Typically, these reference surfaces are located
only in the vicinity of the feed rolls in each option assembly. It would
be advantageous to have a reference surface that minimizes this type of
misalignment between options trays and between an option tray and the
IFD.

[0029] Included in each option assembly are a pick mechanism for moving
media from the media tray, a media positioning mechanism and one or more
drive motors for powering the pick mechanism, media positioning
mechanism, and one or more adjustable media restraints such as a side
restraint and a rear restraint to accommodate for different media widths
and lengths. Further included are media sensors for determining when
media is present in the tray, the size of the media and/or the location
of the leading and trailing edges of the media.

[0030] Most pick mechanisms are designed only for mounting in a single
orientation and for feeding media in only a single direction. This is
typically achieved through the use of a one-way clutch in the pick
mechanism; although other prior art pick mechanisms employ no clutch even
though media is fed in a single direction. With both the clutchless and
clutched pick mechanisms, their design envisions only a single mode or
orientation of mounting. Because an option assembly may be used with more
than one type or model of IFD, it would be desirable to have a single
pick mechanism that could be mounted in a variety of orientations and
provide media feeding in more than one direction.

[0031] Conventional pick mechanisms are usually mounted over the media in
the media tray on one or more steel rods that extend between the sides of
the media tray. With such mounting arrangements it is difficult to remove
or repair the pick mechanism and usually requires the intervention of a
skilled technician. It would be advantageous if the pick mechanism could
be easily removed and reinstalled by a user if repair or replacement were
needed. Lastly, conventional pick mechanisms are designed to provide a
normal force on the topmost media sheet to be fed that is sufficient to
overcome friction with the media sheet immediately beneath. If the
rotational direction of these pick mechanisms were reversed, the force
would cause the trailing edge of the media sheet to be driven into the
rear media restraint damaging the trailing edge. It would be advantageous
to have a pick mechanism that could reduce or eliminate such damage.

[0032] For media trays that employ elevator or lift plate systems to
position media, e.g. to raise the media into a pick position, a single or
multiple motors may be used. With prior systems when the media tray was
removed for refilling, the user was required to manipulate the media
prior to be able to add more. For example, the user had to press down on
the media to lower the elevator until caught by a latch. It would be
advantageous to have a drive system that could operate both the pick
mechanism and the elevator or lift plate with a common motor while also
providing the user with a consistent presentation of the media in the
media tray when the media tray is removed for refilling. This would
reduce manufacturing cost, operating cost and lower weight and energy
usage. Further it would be advantageous to utilize a lift plate that
reduces the uncertainty in the location of the leading edge of the media
as it indexed upward into the picking position.

[0033] It would also be advantageous to have a pick mechanism that would
reduce the variability in positioning the leading edge of the media. This
would allow for the spacing between fed media sheets to be reduced. This
is also referred to as "interpage gap." Reducing interpage gap would
increase media throughput without increasing the speed of the system and
help to lessen wear and tear.

[0034] Media trays have a media dam integrally formed in their front wall
that is used to help direct the fed media into the media path. Typically
such media dams are at an obtuse angle to the direction of the initial
movement of the media being picked. Media dams are known to include wear
strips on their front or face. Wear strips are slightly raised surfaces
on the front face extending vertically along the surface of the media dam
in contact with the picked media and help to decrease friction and aid in
corrugating the fed media. Separator rollers are typically provided
downstream of the media dam within the housing of the option assembly
above the RMIT or in the IFD above the RMIT therein. The separator
rollers usually include a pair of opposed rollers forming a nip
therebetween driven in the same direction so that one roller stops misfed
sheets and the other allows a topmost sheet to be fed. They are used to
reduce the chance of media misfeeds such as multiple feeds and shingling.
In some instances, separator rollers of one type are changed out to
another type depending on media type to be fed from the media tray.
Because of their downstream location in the housing, this is at times an
awkward process. Further, the location of the separator roller downstream
of the media dam outside of the media tray means that for a misfed sheet,
there is greater uncertainty in determining the location of the leading
edge of the misfed media sheet. It would be advantageous to have a media
dam that includes the separator rollers and still further is removably
mounted in the media tray so as to be easily uninstalled and reinstalled
by a user, to easily change the type and configuration of the separator
rolls, and to reduce uncertainty in locating the leading edge of the
media sheet of the media to be fed.

[0035] Prior pick mechanisms were designed to swing down into the media
tray and onto the media stack. This means that the pick mechanism had to
be long enough to reach the bottom of the media tray. Also, this means
that the overall weight of the pick mechanism would be greater than a
system where the pick mechanism does not need to travel to the media tray
bottom. A drawback of this arrangement is that when compressible media,
such as envelopes or labels having RFID tags, are being fed out of the
media tray, the normal force provided by the pick mechanism is greater
than needed with the result that the pick mechanism tends to dig into the
compressible media further compressing the compressible media which will
not separate. Even when an elevator is used to lift the media stack up to
the pick mechanism, meaning that the pick mechanism can be shorter and
lighter, a similar result occurs. Limiting the travel of the elevator
tray does not correct this issue because the end result remains a
compliant pick mechanism picking compliant media. In those IFDs where a
vertical wall joins the media dam to the bottom of tray, the pick
mechanism may compress the media to the point where it then feeds the
media directly into the vertical wall thereby prohibiting the media from
making it to the inclined media dam portion. For successful compressible
media picking to occur, the picking system requires that there be only
one compliant element. With both configurations, for normal media, the
media and tray or media and elevator are non-compliant elements while the
pick mechanism is the compliant element. Whereas for either
configuration, when compressible media is present, both the compressible
media and the pick mechanism are compliant elements. It would be
advantageous to have a pick mechanism that can work reliably with either
compressible media or non-compressible media.

[0036] In another aspect of media feed systems, determination of the
location of the top of the media stack is important. For media elevating
trays, when the tray is removed and reinserted, the location of the top
of the media stack must be determined. This aids in determining the
position of the leading edge of the media sheet that will be fed into the
media path. Prior systems use a contact sensor or mechanical gas gauge
hardware linkage which references the top of media stack or the lifting
plate. It would be advantageous to have a media feed system where such
sensors or linkages can be eliminated.

SUMMARY OF THE INVENTION

[0037] A method for positioning and feeding media into a media feed path
according to one example embodiment includes moving a first media sheet
from the top of a stack of media sheets in a media storage location in a
media process direction from an initial pick position into a media feed
path leaving a second media sheet at the top of the stack of media
sheets. In the media storage location, the second media sheet is moved
opposite the media process direction away from an entrance to the media
feed path until a leading edge of the second media sheet reaches a known
predetermined position in the media storage location. After the leading
edge of the second media sheet reaches the known predetermined position,
the second media sheet is moved in the media process direction from the
stack of media sheets into the media feed path.

[0038] A method for positioning and feeding media into a media feed path
according to a second example embodiment includes rotating a pick
mechanism in a first direction to move a first media sheet from the top
of a stack of media sheets in a media storage location in a media process
direction from an initial pick position into a media feed path leaving a
second media sheet at the top of the stack of media sheets. The pick
mechanism then rotates in a second direction opposite the first direction
to move the second media sheet opposite the media process direction away
from an entrance to the media feed path until a leading edge of the
second media sheet reaches a known predetermined position in the media
storage location. After the leading edge of the second media sheet
reaches the known predetermined position, the pick mechanism rotates in
the first direction to move the second media sheet in the media process
direction from the stack of media sheets into the media feed path.

[0039] A method for positioning and feeding media into a media feed path
according to a third example embodiment includes rotating a pick
mechanism in a first direction to move a first media sheet from the top
of a stack of media sheets in a media storage location in a media process
direction from an initial pick position into a media feed path. A leading
edge of the first media sheet is moved over a separator roller downstream
from the initial pick position and rotating in a second direction
opposite the first direction to separate a second media sheet from the
first media sheet directly beneath the first media sheet in the stack of
media sheets if the second media sheet is double fed with the first media
sheet when the first media sheet is moved from the stack of media sheets.
The pick mechanism rotates in the second direction to move the second
media sheet along the top of the stack of media sheets opposite the media
process direction away from an entrance to the media feed path until a
trailing edge of the second media sheet contacts a restraining member in
the media storage location adjacent to the stack of media sheets opposite
the entrance to the media feed path. After the second media sheet
contacts the restraining member, the pick mechanism rotates in the first
direction to move the second media sheet from the stack of media sheets
into the media feed path.

[0040] In some embodiments, a lift plate supporting the stack of media
sheets is raised when the pick mechanism is rotated in the second
direction. Embodiments include those wherein the lift plate is held in
place when the pick mechanism is rotated in the first direction.

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The above-mentioned and other features and advantages of this
invention, and the manner of attaining them, will become more apparent
and the invention will be better understood by reference to the following
description of embodiments of the invention taken in conjunction with the
accompanying drawings, wherein:

[0042]FIG. 1 is a schematic view of an imaging system according to one
example embodiment;

[0043] FIG. 2 is an illustration of an image forming device according to
one example embodiment;

[0044]FIG. 3 is an illustration of the image forming device of FIG. 2
with the addition of an option assembly;

[0045]FIG. 4 is an illustration of the image forming device of FIG. 3
with the addition of another option assembly;

[0046]FIG. 5 is an illustration of a RMIT with a pick mechanism and drive
system according to one example embodiment;

[0047]FIG. 6 is a top view of the RMIT, pick mechanism and drive system
of FIG. 5;

[0048] FIG. 7 is an illustration of a housing for an option assembly with
the RMIT removed according to one example embodiment;

[0049] FIG. 8 is an illustration of a detachable pick mechanism according
to one example embodiment;

[0050] FIG. 9 is a view of the pick mechanism shown in FIG. 8 with side
plate removed;

[0051] FIG. 10 is a planar section view of the pick mechanism shown in
FIG. 8 taken along line 10-10 of FIG. 8;

[0052] FIGS. 11 and 12 illustrate the pick mechanism shown in FIG. 8 in
two different mounting orientations;

[0053] FIGS. 13A and 13B are section views of the pick axle assembly shown
in FIG. 12 taken along line 13A-13A through a pick wheel and 13B-13B
through a front portion of transmission housing of FIG. 12;

[0054] FIG. 14 is a perspective view of a drive mechanism connected to a
lift plate according to one example embodiment;

[0055] FIG. 15 is a section view of a drive mechanism and a RMIT according
to one example embodiment;

[0056] FIG. 16 is a perspective view of a drive mechanism and a removable
pick mechanism according to one example embodiment;

[0057] FIG. 17 is a perspective view of a drive transmission according to
one example embodiment;

[0058] FIG. 18 is a side elevation view a drive transmission according to
one example embodiment;

[0059] FIG. 19 is a side elevation view of a motor coupled to an encoder
wheel according to one example embodiment;

[0060] FIG. 20 is a section view of a RMIT according to one example
embodiment with media therein;

[0061] FIG. 21 is a section view of a RMIT according to one example
embodiment with media therein;

[0062] FIG. 22 is a perspective view of a pick mechanism and drive
mechanism according to one example embodiment;

[0063] FIG. 23 is a section view of a RMIT with a lift plate in a raised
position according to one example embodiment;

[0064] FIG. 24 is a section view of media being fed from a RMIT according
to one example embodiment;

[0065] FIG. 25 is a perspective view of a drive mechanism engaged with a
lift plate of a RMIT according to one example embodiment;

[0066] FIG. 26 is a perspective view of the drive mechanism of FIG. 25
disengaged from the lift plate;

[0067] FIG. 27 is a perspective view of a drive mechanism having a lifter
according to one example embodiment;

[0068] FIG. 28 is a perspective view of a pick mechanism and a drive
mechanism engaged with a lifting surface of a RMIT according to one
example embodiment;

[0069] FIG. 29 is a perspective view of the pick mechanism and drive
mechanism of FIG. 28 disengaged from the lifting surface;

[0070]FIG. 30 is a section view of a RMIT illustrating an installed
removable media dam according to one example embodiment;

[0071] FIG. 31 is a section view of a RMIT illustrating a partially
removed removable media dam according to one example embodiment;

[0072] FIG. 32 is a section view of the bottom of a removable media dam
showing separator rollers about to be attached to a drive shaft according
to one example embodiment;

[0073] FIG. 33 is a section view of the bottom of a removable media dam
with separator rollers attached according to one example embodiment;

[0074] FIGS. 34A and 34B are an alternate arrangement of separator rollers
in a removable media dam;

[0075] FIG. 35 is a section view of the RMIT illustrating a feed through
channel and a filled media storage location according to one example
embodiment;

[0076] FIG. 36 is an embodiment of an RMIT having a separator roller
performing both media separation and pass through media feeding;

[0077] FIGS. 37 and 38 illustrate a media edge guide reference system
according to one example embodiment;

[0078] FIGS. 39A and 39B illustrate the front and back surfaces of a
portion of the media edge guide reference system according to one example
embodiment;

[0079] FIG. 40 illustrates the arrangement of portions of the media edge
guide reference system within an option housing according to one example
embodiment;

[0080] FIGS. 41 and 42 illustrate the alignment between two portions of
the media edge guide reference system of FIGS. 37 and 38 as a media tray
moves from an open position to an inserted position with an option
housing;

[0081] FIG. 43 illustrates another portion of the media edge guide
alignment system of FIGS. 37 and 38 within IFD 2;

[0082] FIG. 44 is an electrical schematic of the sensors and motors used
in the media input feed system of IFD 2 and option assemblies 50
according to one example embodiment;

[0083]FIG. 45 is a schematic representation of media feeding from an RMIT
according to one example embodiment; and

[0084] FIG. 46 is a graph of separation force versus distance from the top
of the media to the separation point according to one example embodiment.

DETAILED DESCRIPTION

[0085] It is to be understood that the present application is not limited
in its application to the details of construction and the arrangement of
components set forth in the following description or illustrated in the
drawings. The invention is capable of other embodiments and of being
practiced or of being carried out in various ways. Also, it is to be
understood that the phraseology and terminology used herein is for the
purpose of description and should not be regarded as limiting. The use of
"including," "comprising," or "having" and variations thereof herein is
meant to encompass the items listed thereafter and equivalents thereof as
well as additional items. Unless limited otherwise, the terms
"connected," "coupled," and "mounted," and variations thereof herein are
used broadly and encompass direct and indirect connections, couplings,
and mountings. In addition, the terms "connected" and "coupled" and
variations thereof are not restricted to physical or mechanical
connections or couplings.

[0086] In addition, it should be understood that embodiments of the
invention include both hardware and electronic components or modules
that, for purposes of discussion, may be illustrated and described as if
the majority of the components were implemented solely in hardware.
However, one of ordinary skill in the art, and based on a reading of this
Detailed Description, would recognize that, in at least one embodiment,
the electronic based aspects of the invention may be implemented in
software. As such, it should be noted that a plurality of hardware and
software-based devices, as well as a plurality of different structural
components may be utilized to implement the invention. Furthermore, and
as described in subsequent paragraphs, the specific mechanical
configurations illustrated in the drawings are intended to exemplify
embodiments of the invention and other alternative mechanical
configurations are possible.

[0087] As used herein, the term "communications link" is used to generally
refer to structure that facilitates electronic communication between
multiple components, and may operate using wired or wireless technology.
While several communication links are shown, it is understood that a
single communication link may serve the same functions as the multiple
communications links that are illustrated. As used herein, the term media
width refers to the dimension of the media that is transverse to the
direction of the media path. The term media length refers to the
dimension of the media that is aligned to the direction of the media
path. The media is said to move along the media path and the media path
extensions from an upstream location to a downstream location as it moves
from the media trays to the output area of the IFD. For each option tray,
the top of the option tray is downstream from the bottom of the option
tray. Conversely, the bottom of the option tray is upstream from the top
of the option tray. Further, the media is conveyed using pairs of rollers
that form nips therebetween. The term "nip" is used in the conventional
sense to refer to a nip formed between two rollers that are located at
about the same point in the media path and have a common point of
tangency to the media path. With this nip type, the axes of the rollers
are parallel to one another and are typically, but do not have to be,
transverse to the media path. For example, a deskewing nip may be at an
acute angle to the media feed path. The term "separated nip" refers to a
nip formed between two rollers that are located at different points along
the media path and have no common point of tangency with the media path.
Again the axes of rotation of the rollers having a separate nip are
parallel but are offset from one another along the media path. Nip gap
refers to the space between two rollers. Nip gaps may be open, where
there is an opening between the two rollers, zero where the two rollers
are tangentially touching or negative where there is an interference
between the two rollers. As used herein, the leading edge of the media is
that edge which first enters the media path and the trailing edge of the
media is that edge that last enters the media path. Depending on the
orientation of the media in the media trays, the leading/trailing edges
may be the short edge of the media or the long edge of the media, in that
most media is rectangular. Further relative positional terms are used
herein. For example, "superior" means that an element is above another
element. Conversely "inferior" means that an element is below or beneath
another element. "Media process direction" describes the movement of
media within the imaging system as is generally meant to be from an input
toward an output of the imaging system 1. The explanations of these terms
along with the use of the terms "top," "bottom," "front," "rear," "left,"
"right," "up," and "down" are made to aid in understanding the spatial
relationship of the various components and are not intended to be
limiting.

[0088] Referring now to the drawings and particularly to FIGS. 1-3, there
is shown a diagrammatic depiction of an imaging system 1 with an option
assembly. As shown, imaging system 1 may include an IFD 2, an optional
computer 16 and/or one or more option assemblies 50 attached to the IFD
2. Imaging system 1 may be, for example, a customer imaging system, or
alternatively, a development tool used in imaging apparatus design. IFD 2
is shown as a multifunction machine that includes a controller 3, a print
engine 4, a printing cartridge 5, a scanner system 6, and a user
interface 7. IFD 2 may also be configured to be a printer without
scanning. IFD 2 may communicate with computer 16 via a standard
communication protocol, such as for example, universal serial bus (USB),
Ethernet or IEEE 802.xx. A multifunction machine is also sometimes
referred to in the art as an all-in-one (AIO) unit. Those skilled in the
art will recognize that IFD 2 may be, for example, an ink jet
printer/copier; an electrophotographic printer/copier; a thermal transfer
printer/copier; other mechanisms including at least scanner system 6 or a
standalone scanner system.

[0089] Controller 3 includes a processor unit and associated memory 8, and
may be formed as one or more Application Specific Integrated Circuits
(ASIC). Memory 8 may be, for example, random access memory (RAM), read
only memory (ROM), and/or non-volatile RAM (NVRAM). Alternatively, memory
8 may be in the form of a separate electronic memory (e.g., RAM, ROM,
and/or NVRAM), a hard drive, a CD or DVD drive, or any memory device
convenient for use with controller 3. Controller 3 may be, for example, a
combined printer and scanner controller. In one embodiment, controller 3
communicates with print engine 4 via a communications link 9. Controller
3 communicates with scanner system 6 via a communications link 10. User
interface 7 is communicatively coupled to controller 3 via a
communications link 11. Controller 3 serves to process print data and to
operate print engine 4 during printing, as well as to operate scanner
system 6 and process data obtained via scanner system 6. Controller 3 may
also be connected to a computer 16 via a communications link 17 where
status indications and message regarding the media and IFD 2 may be
displayed and from which operating commands may be received. Computer 16
may be located nearby IFD 2 or remotely connected to IFD 2. In some
circumstances, it may be desirable to operate IFD 2 in a standalone mode.
In the standalone mode, IFD 2 is capable of functioning without a
computer.

[0090] Controller 3 also communicates with a controller 53 via
communications links 13 and 15. Controller 53 is provided within each
attached option assembly 50. Controller 53 operates various motors housed
within option assembly 50 that position media for feeding, feed media
from media path branches PB into media path P or media path extensions PX
as well as feed media along media path extensions PX and media path P and
control the travel of media along media path P and media path extensions
PX.

[0091] IFD 2 also includes a media feed system 12 having a pick mechanism
300 and removable media input tray 100 for holding media M to be printed
or scanned. Pick mechanism 300 is controlled by controller 3 via
communications link 13. A media path P (shown in dashed line) is provided
from removable media input tray 100 extending through the printing engine
4 and scanner system 6 to an output area, to a duplexing path or to
various finishing devices. Media path P (shown in dashed line) may also
have extensions PX and/or branches PB (shown in dotted line) from or to
other removable media input trays as described herein such as that shown
in option assembly 50. Media path P may include a manual input tray 40
and corresponding path branch PB that merges with the media path P within
IFD 2. Along the media path P and its extensions PX are provided media
sensors 14 which are used to detect the position of the media, usually
the leading and trailing edges of the media, as it moves along the media
path P. Media sensors 14 positioned along media P and its extension PX
are shown in communication with controller 3 via communications link 15.

[0092] FIG. 2 illustrates IFD 2 that includes the integrated removable
media input tray 100 that is integrated into a lower portion of the
housing 20 of IFD 2. Housing 20 has a front 22, first and second sides
24, 26, rear 28, top 30 and bottom 32. User interface 7 comprising a
display 34 and a key panel 36 may be located on the front 22 of housing
20. Using the user interface 7, a user is able to enter commands and
generally control the operation of the IFD 2. For example, the user may
enter commands to switch modes (e.g., color mode, monochrome mode), view
the number of images printed, take the IFD 2 on/off line to perform
periodic maintenance, and the like. A media output area 38 is provided in
the top 30. A multipurpose media input tray 40 folds out from the front
22 of housing 20 which may be used for handling envelopes, index cards or
other media for which only a small number of media will be printed. Hand
grips 42 are provided in several locations on housing 20, such as on
sides 24, 26, along the top of multipurpose media tray 40, and on the
front of RMIT 100. Also various ventilation openings, such as vents 44
are provided at locations on first and second sides 24, 26, and top 30.
Downstream of RMIT 100 in IFD 2 a media sensor 18 is positioned along the
media path P to sense the presence of, as well as the leading and
trailing edges of media being fed from RMIT 100 with IFD 2 as well as
media being from an option assembly 50. The location of media sensor 18
is indicated on FIG. 38.

[0093] FIGS. 3-7 illustrate the addition of an option assembly 50
comprising a RMIT 100, a housing 200 in which RMIT 100 is placed, a pick
mechanism 300, a drive mechanism 400, and a media reference guide system
500. In FIG. 3, a single option assembly 50 has been added while in FIG.
4 two option assemblies 50 have been added. In both figures, the IFD 2 is
at the top of the stack and sits on top of the uppermost option assembly
50. Latches and alignment features are provided as described herein
between adjacent units. An adjacent unit is either an IFD 2 or another
option assembly 50. Additional option assemblies 50 may be added to the
stack. As each option assembly 50 is added, an extension PX to the media
path P is also added. The media path extension PX within each option
assembly 50 is comprised of two branches which eventually merge at a
point above their respective housing 200, either, depending on location
within the stack, within a superior option assembly 50 or within IFD 2
itself.

[0094] Media sheets M are introduced from RMIT 100 and moved along a media
path P during the image formation process. The RMIT 100 is sized to
contain a stack of media sheets M that will receive color and/or
monochrome images. Each IFD 2 may include one or more input options for
introducing the media sheets. Each RMIT 100 may have the same or similar
features. Each RMIT 100 may be sized to hold the same number of media
sheets or may be sized to hold different quantities of media sheets. In
some instances, the RMIT 100 found in IFD 2 may hold a lesser, equal or
greater quantity of media than a RMIT 100 found in an option assembly 50.
As illustrated RMIT 100 is sized to hold approximately 550 pages of 20
pound media which has a media stack height of about 59 mm. With this
media height, RMIT 100 would be considered to be full. If additional
media were added, RMIT 100 would be considered to be overfilled.
Typically RMIT 100 in option assembly 50 is insertable into a housing 200
of another option assembly 50, but this is not a requirement or
limitation of the design.

[0095] Referring to FIGS. 5 and 6, RMIT 100 has a front wall 102, side
walls 104A, 104B, a rear wall 106, and a bottom 108. Attached to the
front of front wall 102 is panel 110 having hand grip 42 therein (See
FIGS. 2-4). Panel 110 is illustrated as being attached to front wall 102
by fasteners 112. Front wall 102 may be further defined by front portion
114 having a height H1, a back portion 116 spaced apart from front
portion 114 and having a height H2 that is less than height H1, with side
portions 118A, 118B adjacent side walls 104A, 104B, respectively,
connecting front and rear portions 114 and 116 defining a cavity 120, and
a top portion 122. In one embodiment, a removable media dam assembly 500
is received into cavity 120 and is attached to a mount provided in front
wall 102 and contains, in some embodiments, a pair of spaced apart
separator rollers 504 projecting through corresponding openings 506 in
media contact surface 502. In other embodiments, a sloped media dam
extends from the top of rear portion 116 to the top portion 122 of front
wall 102 and between side portions 118A, 118B of front wall 102 and may
be molded into the front wall. In either of these embodiments a media
contact surface 502 forms an obtuse angle with the bottom 108. Also the
combination of rear portion 116 and media contact surface 502 may be
referred to as a media dam having a vertical portion (rear portion 116)
and an angled or sloped portion (media contact surface 502). See FIGS.
30-33 and accompanying description for a more detailed description of
removable media dam 500. In front of a media dam, such as removable media
dam 500, a channel 126 is provided to allow for media M to pass through
RMIT 100 from a lower unit to a superior unit.

[0096] Rearward of front wall 102 is media storage location 140 for media
to be fed to IFD 2 and is generally defined by front wall 102 and side
walls 104A, 104B and bottom 108. As illustrated, rear wall 106 encloses
media storage location 140. Alternate embodiments of RMIT 100 may not
include a rear wall 106. Media storage location 140 may be open or
enclosed. Within media storage location 140 are rear and side media
restraints 170, 171, lift plate 172, and lift arm 173. Media M to be fed
is placed on lift plate 172 which is positioned between side walls 104A,
104B and is dimensioned to hold the widest media for which RMIT 100 is
designed to hold. As illustrated, the length of lift plate 172 is shorter
than the length of the longest media for which RMIT is designed in that
most media have a modicum of pliability. Example media sizes include but
are not limited to A6, 81/2''×11'', A4, and 11''×17''. Lift
arm 173 is positioned beneath lift plate 172 and is connected to drive
mechanism 400. Lift arm 173 extends through side wall 104A toward side
wall 104B and is used to elevate lift plate 172 and media M up to pick
mechanism 300 for feeding into media path P. Openings 174, 175 are
provided in lift plate 172 to accommodate the adjustment of rear and side
media restraints 170, 171, which are slidably attached to bottom 108,
while allowing lift plate 172 to be raised or lowered. Opening 176 is
used with a media out sensor mounted on drive mechanism 400. Provided
near the rear end 178 of the lift plate 172 are a pair of opposed pivot
arms 180A, 180B that extend vertically upward from the lift plate 172
parallel to side walls 104A, 104B, respectively. Openings 182A, 182B are
provided adjacent the upper ends of pivot arms 180A, 180B, respectively,
which are received on corresponding bearing posts 184A, 184B provided on
side walls 104A, 104B, respectively. The use of the pivot arms 180A, 180B
raises a pivot axis 185 of lift plate 172 from the bottom 108 to about
the centerline of bearing posts 184A, 184B, a distance of about 30 mm.
When media storage location 140 is at capacity, this places the leading
edge of the topmost media proximate the top of rear portion 116. The
location of axis 185 may be designed such that it would be approximately
at the mid-point of the rated capacity for the RMIT 100. For example, if
a filled RMIT 100 is designed to hold a media stack of about 50 mm in
height then pivot axis 185 would be located at about 25 mm from the top
surface of lift plate 172. Raising pivot axis 185 of lift plate 172 (See
FIG. 14) reduces the amount of fanning or shingling that occurs in the
leading edges of media M as it is raised up to pick mechanism 300 for
feeding and provides near straight-line motion of the leading edges of
the media M. This in turn helps to reduce uncertainty in locating the
leading edge of the media M during media feeding.

[0097] Media restraints 170, 171 are adjustable and lockable within tracks
186, 187 provided in bottom 108 to accommodate various lengths and widths
of media in RMIT 100. Track 186 allows rear media restraint 170 to move
from a distal position near rear wall 106 to a proximal position
approximately midway along side walls 104A, 104B. Track 187 allows side
media restraint 171 to laterally move from a position adjacent side wall
104B to a position approximately 80 mm from side wall 104A. This allows
RMIT 100 to hold a narrow compressible media such as envelopes for
feeding. Side media restraint 171 has at least one vertically extending
media biasing member 188 to bias a topmost portion of the media toward a
side wall 104A for aligning media to the media path P and media edge
reference surface 604. Biasing member 188 may extend the height of side
media restraint 171 or may extend only a portion of its height. Rear
media restraint 170 has a spring-bias angled plate 189 that abuts the
trailing edges of the media and angles or rotates outwardly from the
bottom of rear media restraint 170 while pivoting about an axis near the
top of angled plate 189. Angled plate 189 helps to reduce fanning or
shingling of the leading edges of media M as it is elevated into picking
position within housing 20 or housing 200 by applying greater biasing on
the lower portion of the media to the media process direction than at the
top of angled plate 189.

[0098] Guide rails 190A, 190B are also provided on the side walls 104A,
104B, respectively, in addition to guide rollers 192 located on the
distal end of side walls 104A, 104B near rear wall 106 to assist with
insertion and removal of RMIT 100 from housing 200. In addition, a
lifting surface 193, such as a ramp is also provided on the top of side
wall 104A. Lifting surface 193 (see FIG. 30) is used into conjunction
with a lifter 460 provided in one embodiment of the drive mechanism 400.

[0099] For purposes of clarity, also shown in FIGS. 5 and 6 are pick
mechanism 300 and drive mechanism 400 and their relations to RMIT 100
when installed in housing 200. As illustrated, pick mechanism 300 is
connected to and supported by drive mechanism 400. Drive mechanism 400 is
mounted within housing 200. Other mounting configurations may also be
used.

Housing

[0100] Housing 200 for option assembly 50 is illustrated in FIG. 7. As
illustrated, housing 200 comprises a top 202, generally parallel sides
204A, 204B, and a back 206. Top 202 is fastened to side walls 204A, 204B
by fasteners such as screws. Front and rear alignment posts 208F, 208R
extend vertically from the top of side wall 204A and are aligned with one
another so that a line drawn between them would to be parallel with side
204A. As illustrated posts 208F, 208R extend about 25 mm upwardly from
top 202. Front alignment post 208F is provided on second plate 640 and
fastens to the top of side wall 204A. Rear alignment post 208R is molded
as part of side wall 204A. Front and rear alignment holes 210F, 210R are
molded into and extend vertically from the bottom of side wall 204A and
are aligned with alignment posts 208F, 208R (See FIG. 40). Because front
and rear alignment holes 210F, 210R are molded into side wall 204A, their
positions can be accurately determined and controlled with a minimum of
tolerance stackup from unit to unit lowering vertical misalignment along
media path extensions PX. Front and rear alignment posts 208F, 208R are
received into corresponding front and rear alignment holes 210F, 210R in
the unit which is above it, either another option assembly 50 or IFD 2.
The upper ends of alignment posts 208F, 208R are tapered to provide for
easier insertion. In one embodiment front alignment hole 210F is round
and dimensioned to closely receive alignment post 208F while rear
alignment hole 210R is an oblong opening dimensioned to allow for
movement of rear alignment post 208R parallel to side wall 204A. Hand
grips 42 are provided in the exterior portion of side walls 204A, 204B.
The bottom of housing 200 is an opening 210 generally defined by sides
204A, 204B and back 206. A support 211 extends between the lower proximal
ends of side walls 204A, 204B to maintain the parallelism between side
walls 204A, 204B and define a front edge of opening 210. Rear wall 206 is
provided with a pair of vertical channels 212A, 212 B, each located near
sidewalls 204A, 204B, respectively. Channels 212A, 212B serve as wire
ways for cabling.

[0101] Spring biased hooks 214A, 214B extend vertically from the top of
side walls 204A, 204B, respectively, and serve as latches to secure
option assembly 50 to the unit above. Corresponding latch holes are
provided in the bottom of side walls 204A, 204B of each option assembly
50 and in bottom 32 of housing 20. As an upper unit, e.g., IFD 2 or
another option assembly 50 is lowered onto top of housing 200,
spring-biased hooks 214A, 214B automatically engage with corresponding
latch holes in the unit being installed locking the unit into position on
top of housing 200. A spring biased release actuator 215 is provided in
recess 216 on one or both of side walls 204A, 204 B. As shown, release
actuator 215 is in side wall 204B. Adjacent hooks 214B is a spring-biased
rod 217 vertically mounted within one or both of side walls 204B. As
illustrated rod 217 is mounted in side wall 204B. When an upper unit is
mounted on top of housing 200 and is properly situated, rod 217 will be
depressed into side wall 204B and hooks 214A, 214B will be engaged with
the upper unit. To remove an installed upper unit, a user pulls or slides
release actuator 215 against its bias spring toward the front of housing
200 which rotates hooks 214A, 214B toward rear wall 206 lowering hooks
214A, 214B and disengaging hooks 214A, 214B from the upper unit. At the
same time an end of rod 217 within side wall 204B engages a detent or
recess in release actuator 215 and retains release actuator 215 keeping
hooks 214A, 214B in a lower unengaged position allowing the upper unit to
be lifted off by a single user. As the upper unit is lifted, rod 217
rises due to the spring biasing and releases actuator 215 which springs
back to its starting position. In turn hooks 214A and 214B spring back to
a vertical position ready to be reengaged when an upper unit is again
placed on housing 200. A second rod, a second recess and a second
actuator similar to rod 217, recess 216 and actuator 215, may be provided
in side wall 204A.

[0102] In side wall 204A, on both its top and bottom is an electrical
connector 218 that will allow for communications links 13 and 15 to be
extended into and through each option assembly as it is added. As shown a
male electrical connection is shown on the top of side wall 204A. A
female electrical connector (not shown) is provided on the bottom of side
wall 204A and in bottom 32 of housing 20. In addition, controller 53 is
provided in option assembly 50. Controller 53 is housed in or on side
wall 204A and is in communication with controller 3 in IFD 2 via
communications links 13, 15 and the various sensors 228, 240, 242, 440,
480, 492. Controller 53 also controls operation of motors 250, 404.

[0103] Drive mechanism 400 and pick assembly 300 are also mounted to side
wall 204A below top 202. On interior portions 220A, 220B of side walls
204A, 204B guide tracks 222A, 222B, respectively, and guide rollers 224A,
224B, respectively, are provided and cooperatively engage guide rails
190A, 190B on RMIT 100 and provide support therefor when it is installed.
Media size sensor 228 is also positioned on interior portion 220A. As
shown, media size sensor 228 comprises four switches that are each
actuated by a corresponding actuator 142 located on side wall 104A of
RMIT 100. Actuators 142 are each in turn operated by mechanical linkages
that move when rear media restraint 170 is positioned along tracks 186
within RMIT 100. The state of the switches in media size sensor 228
provides a binary signal to controllers 3, 53 allowing for up to 16
different media lengths to be sensed. Once media length is sensed,
controller 3, 53 associates a media width for a given length. For example
if the length sensed is 11 inches then the associated media width would
be 8.5 inches. Similar associations are programmed for other commonly
used media such as legal media and A4. A drive motor 250 (see FIG. 44),
also termed a feed motor, for driving separator roller 504 and feed
roller 150 is also housed within a recess in side wall 204A. Drive motor
250 drives drive gear 510 which via intermediary gear 158 drives drive
gear 160 of feed roller 150 (See FIGS. 30 and 31).

[0104] Provided in top 202 are a pair of parallel slots 230, 232 that
extend between side walls 204A, 204B that allow for the feeding of media
M through channel 126 or feeding of media passing over media contact
surface 502 from storage location 140, respectively. In one embodiment
the ends of slots 230, 232 adjacent side wall 204A are formed by a
vertical portion of a plate (which is referred to infra as second plate
642) mounted to side wall 204A below top 202. Media sensors 240, 242 are
provided for slots 230, 232, respectively and are mounted underneath top
202. Media sensors 240, 242 detect the presence of as well as the leading
and trailing edges of media passing through slots 230, 232, respectively.
Media sensor 240 is also referred to as the feed through sensor while
media sensor 242 is referred to as a pick sensor. While specific
locations for various elements have been set forth, those locations may
be changed. For example, pick mechanism 300 or drive mechanism 400
mounted in or on side wall 104A or may be mounted on the opposite side
wall, 104B, 204B respectively and is a matter of design choice to one of
skill in the art.

Universal Mount Pick Mechanism

[0105] Referring to FIGS. 8-13B pick mechanism 300 is shown in further
detail. FIG. 8 shows pick mechanism 300 removably mounted to drive
mechanism 400 on pick drive shaft 426 which is a cantilevered shaft
having a free end 430. As illustrated, pick mechanism 300 comprises a
reversible drive transmission 302, a pick axle assembly 320 and a
transmission housing 340 for reversible drive transmission 302. Pick
mechanism 300 is detachably mountable on drive shaft 426. The terms such
as top, bottom, front and rear of pick mechanism 300 are dependent on its
orientation. As used in this description of pick mechanism 300, the terms
top, bottom, front and rear refer to the orientation of pick mechanism
300 as illustrated in FIGS. 8, 9 and 11.

[0106] Drive transmission 304 comprises a drive shaft gear 306 operatively
connected to a pick axle gear 308 via one or more optional intermediary
gears 315. Drive shaft gear 306 slidably engages via center opening 307
with cantilevered drive shaft 426 extending from drive mechanism 400
mounted on housing 20 of IFD 2 or housing 200 of option assembly 50.
Center opening 307 has a plurality of axial grooves 314 about its
circumference. Drive shaft gear 306 may also have a sleeve 312 axially
extending from one or both sides of drive shaft gear 306 into which axial
grooves 314 may extend. Drive shaft 426 may be provided with at least one
spline 428 radially extending therefrom and along a portion of the length
of drive shaft 426. As shown in FIG. 11, two diametrically opposed
splines 428 may be provided. Axial grooves 314 engage with splines 428 to
transfer torque from the drive mechanism 400 to pick mechanism 300 which
rotates pick axle assembly 320 and rotates pick mechanism 300 downward
onto the topmost media in media storage location 140. The plurality of
axial grooves 314 allow a user to more easily and more quickly install
pick mechanism 300 onto drive shaft 426 in the desired orientation than a
pick assembly having axial grooves that match the number of splines 428
provided. The use of splines 428 and axial grooves 314 allow for more
support surface and drive contact surface between drive shaft 426 and
pick assembly 300. Pick axle gear 308 has a center opening 309 having a
key 310.

[0107] In pick axle assembly 320, pick axle 321 has a pick wheel 322
mounted at each end; however other configurations of pick wheels may also
be used, for example a single pick wheel or three pick wheels made be
mounted on pick axle 321. As illustrated, pick wheels 322 are attached
using fasteners, such as screws 334. As one of skill in the art would
recognize, other forms of attachment of pick wheels 322 to pick axle 321
may be used. Each pick wheel 322 is comprised of a drum or hub 330 having
a pick tire 326 mounted thereon. Because pick mechanism 300 is
reversible, each pick tire 326 has bi-directional treads 328 to provide
substantially the same gripping force in either rotational direction.
Drums 330 mount onto pick axle 321 via openings 331 provided therein
using fasteners 334 axially threaded into holes 335 at each end of pick
axle 321. As one of skill in the art would recognize, other forms of
attachment of pick wheels 322 to pick axle 321 may be used, such as for
example, a snap-on type fitting. As illustrated, pick axle 321 has a
keyway 324 extending axially along it length. Drums 330 each have a key
332 extending into opening 331. Pick axle gear 308 having center opening
309 has a key 312 extending into opening 309. Keys 332 of drums 330 and
key 312 of pick axle gear 308 engage keyway 324. The keys/keyway allow
pick axle 321 and pick wheels 322 to be rotated when pick axle gear 310
is rotated. Keyways may be provided on drums 330 and pick axle gear 308
and a key used on pick axle 321. In operation, when drive shaft 426 is
rotated, torque is transferred to drive shaft gear 304 then to pick axle
gear 308 via intermediary gears 315 and then to pick axle 321 which
drives pick wheels 322.

[0108] Drive transmission 304 and pick axle 321 are mounted in
transmission housing 340 having a top 342, a bottom 344, and a side 346
forming a cavity 347 in which gears 306, 308 are housed. Intermediary
gears 315 are mounted on bearing surfaces 352 provided on side 346 in
cavity 347. If sleeve 312 is present, a corresponding sleeve 349 is
provided on the exterior of side 346 and sized to receive sleeve 312
therein. Also with cavity 347 a plurality of heat stakes 350 are formed
on side 346 about the periphery of cavity 347 and project outwardly
beyond transmission housing 340. In one form heats stakes are plastic
rods. A side plate 348 is used to enclose cavity 347. Side plate 348 has
a plurality of openings 351 therethrough that correspond to the plurality
of heat stakes 350. Heat stakes 350 are inserted into openings 351 and
side plate 348 is slid into position to enclosed cavity 347. A heating
element is used to melt the portions of heat stakes 350 that extend
beyond side plate 348 thus sealing side plate 348 to housing 340. As
shown in the figures, heat stakes 350 are illustrated in an unmelted
state. When melted, the exterior ends of heat stakes 350 would appear
flattened similar to bearing surfaces 352. As known in the art, other
forms of fastening side plate 348 to housing 340 may also be used. Heat
stakes 350 provide fastening force similar to screw or rivet but occupy
less space within transmission housing 340.

[0109] A front portion 353 of transmission housing 340 has a front opening
354 extending therethrough through which pick axle 321 is mounted. The
height of front portion 353 is less than the diameter of pick wheels 322,
i.e. the treads 328 of pick tires 326 extend beyond top and bottom of the
front portion 353. As shown, front portion 353 tapers downwardly from top
342 and upwardly from bottom 344. In one form, transmission housing 340
is approximately 70 mm in length, about 25 mm in height, and about 12 mm
in depth; pick axle 321 is approximately 65 mm in length with a diameter
of about 5 mm; drum 330 is about 16 mm in diameter and about 15 mm in
width; pick wheel 322 has a diameter of about 20 mm including pick tire
326. The height of front portion 353 at its highest is about 18 mm. A
rear portion 355 of transmission housing 340 has a rear opening 356
extending therethrough through which drive shaft 426 passes. Additional
sleeves 359 may be provided on the exterior portions of side 346 and side
plate 348 centered over front and rear openings 354, 356. Sleeves 359 on
front portion 353 may be used to provide axial positioning for pick
wheels 322. Sleeve 359 extending axially from side plate 348 may be used
for mounting latch 360 to transmission housing 340.

[0110] Because pick mechanism 300 is easily removable from drive shaft 426
using latch 360, it can be replaced by a user rather than a trained
technician. As illustrated, latch 360 is mounted on the exterior of side
plate 348 and has an opening 361 centered about the free end 430 of drive
shaft 426 allowing latch 360 to be slid onto pick drive shaft 426. Latch
360 engages a circumferential groove 429 provided near free end 430 of
drive shaft 426. Opposed resilient members 368 are pivotally mounted at
pivots 373 on the exterior of latch 360 and have first ends 370 and
second ends 372. First ends 370 flare slightly outward from latch 360 and
are in the form of finger pads with ridges on the outer surfaces. Second
ends 372 having inwardly turned opposed extensions 375 that extend toward
one another. Extensions 375 may overlap, contact or be slightly separated
when latch 360 is not engaged on drive shaft 426. Extensions 375 engage
with circumferential groove 429 and axially position pick mechanism 300
on pick drive shaft 426. A mounting flange 362 with mounting hole 364 is
provided on latch 360. Latch 360 is mounted to side plate 348 using a
heat stake 350 provided on the exterior of side plate 348 that passes
through mounting hole 364. Mounting hole 364 may be two mounting holes
and each having a corresponding heat stake 350. Again the portions of
heat stake 350 extending beyond mounting flange 362 are melted securing
latch 360 to side plate 348.

[0112] A flag 357 also extends outwardly from transmission housing 340 and
is used to change the state of index sensor 480 which is used for feeding
media M from RMIT tray 100. As illustrated, flag 357 extends outwardly
from side 346. While latch 360 and flag 357 are shown as mounted on
opposite sides of transmission housing 340, they can be mounted on the
same side. At least one stop 358 extends from the transmission housing
340 for limiting the rotation of the pick mechanism 300 about the drive
shaft 426. The frame 402 of the drive mechanism 400 includes an abutment
434 disposed adjacent to the pick mechanism 300 such that when the pick
mechanism 300 rotates beyond a predetermined point, the stop 358 contacts
the abutment 434 thereby limiting either the upward or downward rotation
of the pick mechanism 300 about the pick drive shaft 426. In some
embodiments, a pair of diametrically opposed stops 358 extend from the
transmission housing 340 such that the stops 358 limit both the upward
and downward rotation of the pick mechanism 300 about the pick drive
shaft 426. Embodiments include those wherein the stop(s) 358 radially
extend from the sleeve 349. In some embodiments, the sleeve 349 is
tubular in shape. In the example embodiment shown, abutment 434 is an
arcuate member curving around the exterior of sleeve 349 (See FIG. 8). In
this configuration, when the pick mechanism 300 rotates downward beyond a
predetermined point, the bottom stop 358 contacts the abutment 434
thereby limiting the downward rotation of the pick mechanism 300 and when
the pick mechanism 300 rotates upward beyond a predetermined point, the
top stop 358 contacts the abutment 434 thereby limiting the upward
rotation of the pick mechanism 300.

[0113] Pick mechanism 300 has several advantages over prior pick
mechanisms. Because it is reversible, small in length and lightweight, a
clutching mechanism is not required within the drive transmission 304.
This helps to reduce cost and weight of pick mechanism 300.
Reversibility, combined with the dimensioning of pick wheels 322
extending beyond the height of front portion 353, allows pick mechanism
to be rotated 180 degrees end to end from its position shown in FIG. 11
to that shown in FIG. 12 when pick mechanism is mounted on side wall 204A
of housing 200. This is termed a right hand mount when viewed from the
media process direction. Pick mechanism 300 may also be flipped over from
side to side allowing pick mechanism 300 to be mounted on side wall 204B
of housing 200, a left hand mount when viewed from the process direction.
Thus pick mechanism 300 can accommodate right hand mounts, left hand
mounts and from either mount can be oriented such that pick wheels 322
are oriented toward front wall 102 or rear wall 106 of RMIT 100. Because
pick mechanism 300 can accommodate this variety of mounting and operating
orientations, it is termed a universal pick mechanism.

[0114] Plastic, such as acrylonitrile butadiene styrene (ABS) or
polyoxymethylene (POM), may be used for the majority of components in
pick mechanism 300. Pick tires 326 are fabricated from elastomer based
materials to provide gripping forces against media M. Gears 304, 308, 315
used in drive transmission 304 may be made of POM. Because pick mechanism
300 is used in conjunction with lift plate 172 which raises the media M
to pick mechanism 300, it can be made shorter in length than prior art
pick mechanisms used in similar capacity media trays where such pick
mechanisms have to be able to reach the tray bottom. The shorter length
reduces the weight of the pick mechanism 300 over such prior art designs.
For example, pick mechanism 300 has a weight of about 20 grams while a
prior art pick mechanism for a similar capacity media tray had a weight
of about 55 grams. Further, because the rotational travel of pick
mechanism 300 is limited to about 2.5 degrees of rotational travel during
normal media picking, the amount of pick force applied to the topmost
media is more constant over its travel. The combination of stops 358 and
abutment 434 limit the total upward and downward motion of pick mechanism
300 to an arc of about 23 degrees versus about 140 to 160 degrees of
rotation motion for prior art configurations.

[0115] For example, for the present pick mechanism the normal pick force
is about 20 grams at the maximum media height within storage location 140
and about 18 grams at the lower end of its rotational travel versus about
42 grams at the maximum media height and about 45 grams at the tray
bottom for a prior art pick mechanism. This greater force on prior art
pick mechanisms induces more double feeds of media M. To overcome this
prior art, pick mechanisms are counterbalanced using springs that require
adjustment during assembly of the pick mechanism leading to significant
variability in the magnitude of normal pick force. For the present pick
mechanism 300, the primary cause of variance in normal pick force is due
to dimensional variances of its components which provide a slight amount
of variance in weight causing a slight variance in the normal pick force
of about 2 grams. However, due to close dimensional tolerances, the
amount of normal pick force variances caused by weight variances of
components in the present pick mechanism 300 is significantly less than
the amount of variability in the normal pick force of a counterbalanced
pick mechanism. Because normal pick force of pick mechanism 300 is more
uniform over its travel, the problem with double feeds of media is
reduced over prior art pick mechanisms. Another benefit is that
counterbalancing mechanisms can be eliminated and the needed
counterbalancing procedures during assembly can be avoided in almost all
instances.

Drive Mechanism

[0116] With reference to FIGS. 14 to 18, a drive mechanism 400 according
to an example embodiment is shown. A frame 402 mounted to housing 20
supports drive mechanism 400. Drive mechanism 400 includes a common motor
404 that drives pick mechanism 300 and lifts lift plate 172. Drive
transmission 401 is shown having a single input 401A connected to motor
404. Drive transmission 401 includes a first output 401B connected to
pick mechanism 300 and a second output 401C connected to lift plate 172.
While the example embodiment shown includes two outputs 401B, 401C,
additional outputs may be provided as desired for performing additional
functions.

[0117] A drive pinion 406 extends from motor 404 and connects to drive
transmission 401 to transfer rotational force from motor 404 to drive
transmission 401. In the example embodiment shown, drive pinion 406 is
connected to a speed reducer dual gear 408 that includes a larger portion
408A and smaller portion 408B. Pinion 406 is connected to larger portion
408A while smaller portion 408B is connected to an intermediary gear 410.
It will be appreciated that in this configuration, the rotational speed
of intermediary gear 410 is less than the rotational speed of motor 404
and drive pinion 406 as a result of the difference between the
circumferences of larger portion 408A and smaller portion 408B of speed
reducer dual gear 408. Alternatives include those wherein the orientation
of larger portion 408A and smaller portion 408B is reversed so that the
rotational speed of intermediary gear 410 is greater than the rotational
speed of motor 404 and drive pinion 406. Further alternatives include
those wherein speed reducer dual gear 408 is replaced with a simple
intermediary gear so that the rotational speed of intermediary gear 410
is the same as the rotational speed of motor 404 and drive pinion 406.

[0118] A pick mechanism drive gear 412 is connected to intermediary gear
410. Pick mechanism drive shaft 426 is substantially concentric with and
extends from pick mechanism drive gear 412. Drive shaft 426 is positioned
by a pair of bearing sleeves 427 relative to frame 402. Bearing sleeves
427 are each mounted in a respective hole 432 in frame 402 and are
disposed around drive shaft 426 so that drive shaft 426 is free to
rotate. Drive shaft 426 extends from frame 402 in a cantilevered fashion
and includes a free end 430. Pick mechanism 300 is removably mountable on
free end 430 of drive shaft 426. When pick mechanism 300 is mounted on
drive shaft 426, drive shaft 426 transfers rotational force to drive
shaft gear 306 for driving the pick wheels 322. Frame 402 further
includes an abutment 434 adjacent to pick mechanism 300 (See FIG. 8).
Abutment 434 limits the rotational travel of pick mechanism 300 by
providing a hard stop for stops 358 and the rotational motion of the pick
mechanism 300.

[0119] A first clutched gear 414 is connected to first output 401B of
drive transmission 401. In the example embodiment shown, first clutched
gear 414 is positioned around drive shaft 426. A second clutched gear 416
is connected to first clutched gear 414 and second output 401C of drive
transmission 401. First and second clutched gears 414, 416 each include a
one-way clutch. In the example embodiment shown, second clutched gear 416
is connected to an intermediary gear 418 protruding through top of the
side wall 104A of the RMIT 100. Intermediary gear 418 is connected to a
sector gear 422 pivotally mounted in side wall 104A. In the example
embodiment illustrated, intermediary gear 418 is connected to sector gear
422 via an additional intermediary gear 420 in side wall 104A. Lift arm
173 is mounted to sector gear 422 through a radially oriented opening 424
in sector gear 422. Lift arm 173 is slidably disposed between bottom 108
and a bottom surface 172A of lift plate 172. Accordingly, rotation of
sector gear 422 in one direction rotates lift arm upward against bottom
surface 172A thereby rotating lift plate 172 about pivot axis 185.

[0120] The engagement of first clutched gear 414 is opposite the
engagement of second clutched gear 416. Clutched gears 414, 416 are
configured so that when pick mechanism 300 is driven in the media process
direction for feeding media M, lift plate 172 is held in place during
feeding of media. When elevation of lift plate 172 is called for as media
is removed during media feeding, motor 404 rotation is reversed raising
lift plate 172 while reversing the rotation of pick mechanism 300 to be
opposite the media process direction. In the example embodiment shown,
when motor 404 drives the pick mechanism 300 in the media process
direction, first clutched gear 414 is disengaged so that it does not
rotate with drive shaft 426 and second clutched gear 416 is engaged to
hold lift plate 172 in place. When motor 404 drives pick mechanism 300
opposite the media process direction, first clutched gear 414 is engaged
so that it rotates with drive shaft 426 as it is driven by motor 404 and
second clutched gear 416 is disengaged and driven by first clutched gear
414 to rotate sector gear 422. Rotation of the sector gear 422 raises
lift arm 173 and, in turn, raises lift plate 172.

[0121] With reference to FIG. 19, motor 404 includes an encoder wheel 490
that rotates with motor 404 providing encoder pulses indicative of the
rotation of motor 404. As encoder wheel 490 rotates, an encoder wheel
sensor 492 provides an output 494 in the form of pulses to controllers 3,
53 that allows controllers 3, 53 to track the rotation of encoder wheel
490 and motor 404 which may be used to track movement of lift plate 172
and rotation of pick mechanism 300.

[0122] With reference back to FIG. 16, an index sensor 480 having an
output 484 is positioned on frame 402 adjacent to the drive shaft 426. In
the example embodiment illustrated, index sensor 480 is an optical sensor
having an optical path between a pair of opposed arms. However, any
suitable sensor may be used. In operation, lift plate 172 is raised in
indexed moves in order to ensure that the top of the stack of media
sheets is within a desired pick height so that the rotational travel of
pick mechanism 300 remains within a predetermined range of travel as
previously described. When RMITs 100 are inserted into housings 20, 200,
controller 3, 53 analyzes output 484 of the index sensor 480 to determine
whether upward indexing of lift plate 172 is needed. If index sensor 480
is in a first state when RMIT 100 is inserted (FIGS. 20 and 21), indexing
is not required. If index sensor 480 is in a second state, indexing is
required (FIG. 22). In the example embodiment illustrated, if the optical
path of index sensor 480 is blocked by index flag 357 when RMIT 100 is
inserted, no indexing is required. Conversely, if the optical path of
index sensor 480 is unblocked, indexing is required. As will be
appreciated, reverse logic to that described may also be used.

[0123] With reference to FIGS. 23 and 24, in order to index lift plate
172, motor 404 drives pick mechanism 300 opposite the media process
direction and raises lift plate 172 in order to raise the stack of media.
Once the top of the stack of media contacts the pick mechanism 300, the
stack of media pushes pick mechanism 300 up until index flag 357 changes
the state of index sensor 480. After the state of index sensor 480
changes, e.g. from unblocked to blocked, motor 404 continues to rotate
for a predetermined number of encoder pulses until lift plate 172 reaches
a maximum desired pick height. Once lift plate 172 reaches the maximum
desired pick height, pick mechanism 300 is then ready to feed media in
the media process direction. As media M is fed, the height of the media
stack decreases thereby lowering the position of pick mechanism 300.
Eventually, pick mechanism 300 lowers far enough for index flag 357 to
change the state of index sensor 480, e.g. from blocked to unblocked,
thereby signaling that another index is required. Motor 404 once again
drives pick mechanism 300 opposite the media process direction and raises
lift plate 172 to raise the stack of media. In some embodiments, when an
index is required, motor 404 rotates for a predetermined number of
encoder pulses until lift plate 172 reaches the maximum desired pick
height. In other embodiments, motor 404 first raises lift plate 172 until
index flag 357 changes the state of index sensor 480, e.g. from unblocked
to blocked. After the state of index sensor 480 changes, motor 404 then
rotates for a predetermined number of encoder pulses until lift plate 172
reaches the maximum desired pick height. The index moves that occur as a
result of the reduction in the height of the media stack due to media
being fed are referred to as nominal raises or nominal index moves. As
media continues to be fed, nominal index moves are repeated to ensure
that the pick mechanism 300 stays within the desired pick range until all
of the media in RMIT 100 is fed to IFD 2.

[0124] When feeding incompressible media, the feeding system includes only
one compliant element, the pick mechanism 300 which rotates downward
about the drive shaft 426 as it feeds media; both the lift plate 172 and
the incompressible media are non-compliant elements. However, when
compressible media is fed, the media itself is a compliant element.
Feeding difficulty may be encountered when more than one compliant
element exists in the feeding system. In order to feed compressible
media, such as envelopes or RFID labels, using a pick mechanism 300 that
rotates about the drive shaft 426, the force required to buckle the media
must be less than the force required to compress the media. When
compressible media are placed in RMIT 100, depending on the number of
compressible media and the compressibility of the media, initially, the
force required to compress the media may be less than the force required
to buckle and feed the media. As a result, the media will tend to
compress rather than buckle and separate as the compliant pick mechanism
300 continues to rotate downward about the drive shaft 426 and the normal
force applied by the pick mechanism 300 to the media stack continues to
increase. This compression will continue until the force required to
compress the media exceeds the force required to buckle and feed the
media at which point the media will buckle and feed. However, in some
cases, by this point, the pick mechanism 300 will have rotated out of the
desired pick zone.

[0125] Accordingly, in some embodiments, in order to accommodate feeding
of compressible media, the downward rotation of the pick mechanism 300 is
limited. In the example embodiment illustrated, the rotation of the pick
mechanism 300 about the drive shaft 426 is limited when the stop(s) 358
contact the abutment 434 (See FIG. 8). At the point where the downward
rotation of the pick mechanism 300 is limited, the pick mechanism 300 is
converted from a compliant element to a non-compliant element. By
converting the pick mechanism 300 to a non-compliant element, the pick
mechanism 300 is not able to compress the media further. Typically, the
force required to buckle compressible media is less than the force
required to buckle incompressible media because compressible media
generally does not include edge welds. As a result, at the point where
the downward rotation of the pick mechanism 300 is limited, the tackiness
of the pick wheels 322 generally allows the pick mechanism 300 to feed
the media without compressing it further as long as the coefficient of
friction between the wheels 322 and the media is greater than the
coefficient of friction between adjacent media.

[0126] Further, in those embodiments where the inclined media dam 500
includes a substantially vertical wall portion proximate the media
storage location 140 extending downward from the media dam 500, such as
back portion 116 of the front wall 102 (See FIG. 5), the downward
rotation of the pick mechanism 300 is limited at a point above the
intersection between the inclined media dam 500 and the substantially
vertical wall portion. This ensures that when the media is fed by the
pick mechanism 300, it is able to ascend the media dam 500. If the media
were fed below the intersection between the inclined media dam 500 and
the substantially vertical wall portion, the leading edge of the media
would be fed directly into the substantially vertical wall portion which
could result in a misfeed if the media is unable to ascend the
substantially vertical wall portion and reach the media dam 500.

[0127] In some embodiments, in order to permit the feeding of compressible
media, the controller 3 analyzes the state of the index sensor 480 after
each pick is completed. The controller 3 compares the state of the index
sensor 480 after each pick with the state of the index sensor 480 after
the previous pick. When the state of the index sensor 480 changes, for
example, when the index sensor 480 goes from blocked to unblocked, the
controller 3 raises the lift plate 172. If after a pick is completed, the
state of the index sensor 480 is the same as after the previous pick, the
controller 3 directs the pick mechanism 300 to feed the next media sheet.
Analyzing the state of the index sensor 480 between picks allows the
media an opportunity to decompress as the normal force applied by the
pick mechanism 300 decreases. As a result, the controller 3 is able to
ignore changes in the state of the index sensor 480 that occur during a
pick operation as a result of the compression of compressible media.

[0128] With reference to FIGS. 25 and 26, each time RMIT 100 is removed
from the housing 20, drive transmission 401 disconnects from the second
output 401c causing the lift plate 172 to fall to bottom 108 of RMIT 100.
As a result, lift plate 172 is presented to the user in a consistent
manner for re-filling each time RMIT 100 is removed regardless of the
amount of media still remaining in RMIT 100. In the example embodiment
shown, when RMIT 100 is removed, the connection between second clutched
gear 416 and intermediary gear 418 in the side wall 104a is broken. As a
result, each time RMIT 100 is reinserted into housing 20, 200 lift plate
172 must be indexed from bottom 108 of RMIT 100 until pick mechanism
reaches the maximum desired pick height.

[0129] With reference to FIGS. 5, 6, and 27, a media out flag 441 is
mounted on frame 402. Media out flag 441 includes a flag arm 442 and a
media contact arm 446 connected to one another by a connecting rod 448.
Connecting rod 448 has a tab 449 for engaging with a lifter 460 for
lifting media contact arm 446 when RMIT 100 is removed from the housing
20. Media contact arm 446 extends from a first side 402A of frame 402
beneath drive shaft 426 while flag arm 442 extends from opposite side
402b of frame 402. A media out sensor 440 having an output 444 is
disposed on the side 402B of frame 402 opposite drive shaft 426. In the
example embodiment illustrated, media out sensor 440 is an optical sensor
having an optical path between a pair of opposed arms. However, any
suitable sensor may be used. In operation, when media M is present in
storage location 140, media contact arm 446 rests on the top of the media
stack. When media contact arm 446 rests on the media stack, flag arm 442
is held above the opposed arms of media out sensor 440. When RMIT 100
runs out of media, media contact arm 442 falls through opening 176 in
lift plate 172 thereby dropping flag arm 442 into the arms of media out
sensor 440 and changing output 444 of media out sensor 440 to indicate
that RMIT 100 is out of media.

[0130] With reference to FIGS. 28 and 29, drive mechanism 400 includes a
lifter 460 for lifting pick mechanism 300 and media contact arm 446 when
RMIT 100 is removed so that they are not caught by rear wall 106 as it
passes below. Lifter 460 is mounted around drive shaft 426 and first
clutched gear 414. Lifter 460 has a hole 469 in each of its ends 468 to
receive the drive shaft 426. Lifter 460 includes a first arm 462 for
engaging with tab 449 of media out flag 441 and a second arm 464 for
engaging with pick mechanism 300. A biasing spring 470 biases lifter 460
toward a home position where first arm 462 is engaged with and depresses
tab 449 so that media contact arm 446 is raised and second arm 464 is
engaged with and raises pick mechanism 300. A camming surface 466 extends
from lifter 460 underneath frame 402. When RMIT 100 is inserted into the
housing 20, 200 lifting surface 193 of side wall 104A engages with and
causes camming surface 466 to rotate. Rotation of camming surface 466
that results from engagement with lifting surface 193 overcomes the
biasing force of biasing spring 470 to rotate lifter 460. This rotation
causes first arm 462 to lift off of tab 449 allowing media contact arm
446 to drop freely and causes second arm 464 to lower and disengage from
pick mechanism 300 allowing pick mechanism 300 to rotate about drive
shaft 426.

Removable Media Dam

[0131] Referring to FIGS. 30-33, removable media dam 500 is illustrated.
In FIG. 30, removable media dam 500 is shown mounted in cavity 120 in
front wall 102 behind channel 126. Mounts are provided on both front wall
102 and on removable media dam to allow for the detachable mounting of
removable media dam in RMIT 100. On media contact surface 502, a pair of
spaced apart, rotatably mounted separator rollers 504 are provided in
corresponding openings 506 of removable media dam 500. A portion of the
surface of each separator roller 504 radially extends through the
corresponding opening 506. When the media dam is molded into front wall
102, separator rollers are also provided as described for the removable
media dam. Separator rollers 504 may have various tread patterns, like
those on a tire, on their surfaces which contact the media being fed from
RMIT 100. The patterns are a matter of design choice. A plurality of
slightly raised wear strips 508 are provided on media contact surface
502. The surfaces of wear strips 508 may have frictional features such as
transverse ridges or steps mold therein or provided in a member that is
affixed to the surface of wear strips 508. Drive gear 510 is attached to
an end of shaft 511 on which separator rolls 504 are mounted. Drive gear
510 also connects, via intermediate gear 158, with drive gear 160 which
drives feed roller 150. Backup roller 152 is spring-biased against feed
roller 150 forming a nip 154 therebetween (See FIGS. 15 and 35). In one
embodiment, drive gear 160, feed roller 150, backup roller 152, and
intermediate gear 158 may be mounted to first plate 602 that is attached
to side portion 118A. A motor (not shown) provided in housing assembly
200 provides torque for rotating gears 510, 158, and 160.

[0132] In FIG. 31, removable media dam 500 is shown partially removed.
Details of latch mechanism 512 according to one embodiment can be better
seen. An opening in a side panel 520 of media dam 500 serves as latch
catch 518. Actuator 514 has opposed side rails 521 slidably received into
guide channels 522. A spring (not shown) is provided at a distal end of
actuator 514 to bias actuator 514 toward side wall 104A and to bias latch
hook 516 into latch catch 518. Stops (not shown) prevent actuator 514
from being pushed out of RMIT 100. To remove removable media dam 500,
actuator 514 is depressed by a user. This allows latch hook 516 to
release from latch catch 518, allowing a user to lift removable media dam
500 upwards and out of cavity 120 without the use of tools. Thus in this
embodiment, removable media dam 500 is referred to as a tool-free
removable media dam. A second side panel 524, opposite the first side
panel 520 of the removable media dam 500 has at least one post 526
extending outwardly therefrom which is received in a corresponding
opening in a wall of cavity 120. As shown, two posts 526 are illustrated
(See FIG. 32). To insert the same or another removable media dam having
different configuration of separator rollers 504 and or a different media
contact surface 502 or wear strips 508, a user would insert posts 526
into their corresponding openings in the wall forming cavity 120.
Removable media dam is then lowered into cavity 120 with latch hook 516
snapping into latch catch 518 completing installation of removable media
dam 500. While latching assembly 512 is illustrated, one of skill in the
art would recognize that other forms of mounts and snap fit mechanisms
can be used to the same effect and that the illustrated latching assembly
is not considered to be a limitation of the design.

[0133] Removable media dam 500 may also be installed using conventional
fasteners such as screws. In such an embodiment, latch assembly 512 would
not be provided and removable media dam 500 would not be referred to as a
tool-free removable media dam.

[0134] FIGS. 32 and 33 illustrate one embodiment of the attachment of
separator rollers 504 to removable media dam 500. A cavity 501 is
provided on the underside of removable media dam 500 for the mounting of
separator rollers 504. As shown, shaft 511 which passes through an
opening in side panel 520 then through one of the separator rollers 504,
then through bearing 528 and then the second separator roller 504.
Transverse holes 529 are provided in shaft 511 to receive pins 530. Each
separator roller 504 comprises a hub 532 and tire 534 having treads 535.
Hubs 532 are provided with channels 536 that engage pins 530 that are
inserted into holes 529. Hubs 532 are slip fit onto pins 530 by pulling
shaft 511 outwardly from side panel 520. Support ribs 538 are provided in
cavity 501 to stiffen removable media dam 500. Tabs 540 extending from
the lower rear edge of media dam 500 slide in behind the upper edge of
rear portion 116 to help stiffen rear portion 116. Other configurations
for separator rollers 504 may be used, for example one separator roller
or 3 or more separator rollers.

[0135] Removable media dam 500 allows a user to replace a removable media
dam having worn separator rollers 504 with a new removable media dam
having new separator rollers, or to use separator rollers having a
different tread, or a media dam having a different number or different
configuration of separator rollers without the need to have different
RMITs, or a different number configuration of wear strips or patterns
used on the wear strips. FIGS. 34A and 34B show two embodiments of a
removable media dam having different configurations for separator rollers
504. FIG. 34A shows for media dam 500A, a separator roller 504A aligned
with each the pick wheel 322 of pick mechanism 300. FIG. 35B shows for
media dam 500B, the separator rollers 504B being transversely or
laterally offset from pick tires 302 of pick mechanism 300.

[0136] As illustrated, separator rollers 504 are positioned opposite the
pick wheels 322. The separator rollers 504 rotate in a direction counter
to the media process direction of the pick wheels 322 when pick mechanism
300 is feeding media M from RMIT 100. In some embodiments, the separator
rollers 504 are rotated counter to the media process direction throughout
the duration of each pick cycle. Separator rollers 504 in some
embodiments rotate at a slower speed than that of the pick wheels 322,
such as between 40-60 percent of the rotational speed of the pick wheels
322. The counter rotation of the separator rollers 504 helps to prevent
shingling and misfeeds of media. Referring also to FIGS. 24 and 45,
during shingling a second or following sheet 704 is also fed from the top
of the media stack but its leading edge 704L is slightly behind or
shingled with respect to topmost sheet 702 being fed. As both media
approach the separator rollers 504, the leading edge 702L of topmost
sheet 702 strikes the surface of the separator roll tangentially and
continues across the surface. If topmost sheet 702 is skewed when it
reaches the separator rollers 504, then one side of the leading edge 702L
will reach the separator rollers 504 before the other thereby
encountering a drag force that will correct the skew. The leading edge
704L of shingled media 704 strikes the surface of the separator rollers
504 in a normal direction and is stopped by separator rollers 504 while
the topmost media 702 continues being fed. The separator rollers 504
return the second media sheet 704 to a separation point upstream and
adjacent the separator rollers 504.

[0137] Separator rollers 504 and pick wheels 322 form what is termed an
open nip in that as shown the separator roller 504 is downstream and
spaced away from pick wheels 322. The use of an open nip allows pick
mechanism 300 to be placed in a variety of positions such as being center
referenced or being edge referenced as illustrated. An advantage of using
an open nip design lies in its ability to deskew media as just described.
Also, mounting pick mechanism 300 adjacent to side wall 104A leads to a
more compact design and the ability to more reliably feed narrow media in
media trays not incorporating media biasing systems that center media
about the pick mechanism. In prior art systems, the pick mechanism was
positioned about a front-to-back centerline of the media storage area
within the media tray in order to minimize skewing forces on the media
caused by the pick mechanism when feeding media.

[0138] The tangential point of contact between the topmost media sheet and
separator rollers 504 is spaced vertically above the tangential point of
contact between the topmost media sheet and the pick wheels 322. As
illustrated, the distance between the surfaces of pick wheel 322 and
separator rollers 504 is about 10 mm. In prior art, the separator roller
is placed further downstream of the pick point of the media, for example
50-150 mm, which increases the amount of uncertainty it the location of
the leading edge of the shingled media and also increases the overall
size of the entire imaging system 1. In such prior art arrangements, a
separate backup roller is provided with the separator roller forming a
nip therebetween. By use of the open nip arrangement between pick wheels
322 and separator rollers 504, the amount of leading edge uncertainty is
reduced by a factor of 5 or more. This in turn allows the interpage gap
spacing between successive sheets to be reduced increasing media feed
through for a given speed. The open nip allows for removal of the
separator load after pick mechanism 300 is turned off which removes any
drag caused by separator rolls 504 on the media that may cause skewing.
Also a backup roller can be eliminated from the media path.

[0139] With reference to FIG. 35, in front of a media dam, such as
removable media dam 500, a channel 126 is provided to allow for media M
to be fed through RMIT 100. Channel 126 is positioned between side walls
104 having a length and width to accommodate various widths and
thicknesses, respectively, of media M being fed to IFD 2. As illustrated,
the depth of channel 126 extends the first height H1 from the top portion
122 through the bottom 108. Channel 126 along with corresponding slots in
housing 200 form a media path extension PX allowing media to be fed
through option assembly 50.

[0140] Channel 126 comprises a front wall 128, a rear wall 129, a bottom
opening 130 and a top opening 131. In one embodiment, the width of bottom
opening is greater than the width of the top opening. Front wall 128 of
channel 126 extends vertically between the top and bottom openings 130,
131. Rear wall 129 of channel 126 has an angled section 132 that tapers
upwardly from bottom opening 130 toward top opening 131 of channel 126
where it connects with a vertical section 133 of rear wall 129 that
extends to top opening 131. Corresponding openings 134, 135 are provided
in rear and front walls 129, 128 respectively of channel 126. Feed roller
150 is rotatably mounted on shaft 151 in cavity 120 and has a portion of
its surface projecting through opening 134 into channel 126. One end of
shaft 151 passes through an opening on first plate 602 on which drive
gear 160 is mounted. Backup roller 152 is rotatably mounted in carrier
161 in opening 135 and its surface forms a nip 154 with feed roller 150
in channel 126. Backup roller 152 may be biased toward feed roller 150 by
a biasing means, such as a spring 156 positioned between carrier 161 and
a wall of opening 135. In one embodiment, carrier 161 is pivotally
mounted to first plate 602 at post 153 (See FIGS. 39A, 39B).

[0141] The rotational axes of the feed roller 150 and the backup roller
152 are spaced vertically below the rotation axis of the separator
rollers 504. This minimizes the height of the RMIT 100 and in turn the
height of the IFD 2. Embodiments include those wherein the feed roller
150 and the separator rollers 504 are connected to a common drive source.
As shown in FIGS. 30 and 31, the separator roller drive gear 510 which
drives the separator rollers 504 is connected to drive gear 160 via
transfer gear 158. Drive gear 160 is attached to an end of the shaft (not
shown) on which the feed roll 150 is mounted. As discussed above, a motor
(not shown) provided in housing assembly 200 provides torque for rotating
gears 510, 158, and 160.

[0142] With reference to FIG. 36, an alternative embodiment is shown
wherein the nip 154 is formed by a separator roller 504 and backup roller
152. In this configuration, the separator roller 504 aids in separating
shingled fed media and functions as the feed roller to the nip 154.
Accordingly, a separate feed roller 150 is no longer necessary. Further,
because the separator roller 504 is driven by drive gear 510, transfer
gear 158 and drive gear 160 may be eliminated. A first portion of the
outer surface of the separator roller 504 extends radially through
opening 506 into the media feed path. A second portion of the outer
surface of the separator roller 504 extends radially through opening 134
in rear wall 129 into channel 126. Backup roller 152 extends radially
through opening 135 in front wall 128 into channel 126. Backup roller 152
may be biased toward separator roller 504 by a biasing means, such as a
spring 156.

[0143] With reference back to FIGS. 30 and 31, a plurality of spaced
vertical ribs 136 are provided on the surface of the front and rear walls
128, 129 of channel 126. Ribs 136 are used to support the media passing
through channel 126. Ribs 136 are spaced across the width of channel 126
so that one or more ribs 136 will fall within the width of most common
media types that will be fed from RMIT 100 and that one of those ribs 136
will be within a few millimeters of the edge of the media M being fed.
With reference to FIGS. 37 and 38, in some embodiments, one end of
channel 126 is formed by a plate 602 attached to side wall 104A. In other
embodiments, a vertically oriented rectangular post 138 is provided at
the end of channel 126 and adjacent side wall 104A and abuts a media
reference surface 604 of first plate 602. Plate 602 and post 138, when
provided, are part of a media reference edge guide system 600 that keeps
the media M in proper alignment as it travels through or into media path
extensions PX found in an option assembly 50 and on to media path P of
IFD 2.

[0144] In prior art design, the media feed roller was placed above the
media exit from the media contact surface 502 and above the top of
channel 126 in housing 20 or housing 200. This placement increased the
overall height of the option assembly by about 20 mm over the presently
described option assembly 50. Typically image forming systems may
employee 3 to 5 option assemblies or more. For such systems this means
option assembly 50 saves 60 to 100 mm or more in the overall height of
the image forming system 1. With the present arrangement, feed roller 150
of a given unit pulls media from the unit positioned beneath and feeds it
to the unit above it.

[0145] Referring to FIGS. 37-43, a substantially continuous media edge
reference guide (MERG) system 600 is illustrated. In prior art designs
the media edge reference guides were subject to large vertical gaps and
vertical misalignment from unit to unit within the media path P and path
extension PX due to tolerance stack ups of components within a unit. As
viewed in FIGS. 37 and 38, vertical misalignment refers to a left or
right displacement from the media path P or media path extension PX. In
FIGS. 37 and 38 only the reference guide system elements of the media
path P within IFD 2 and media path extensions PX within option assemblies
50-1, 50-2 are shown for purpose of clarity. In FIGS. 37 and 38 there is
shown a MERG system 600 for IFD 2 mounted on top of two option assemblies
50-1, 50-2. Boundaries between the various units in the stack are
indicated by the dashed lines 601 in FIG. 37. Beginning at the bottom of
each figure and working vertically upward there is a first plate 602 then
a second plate 640 for option assembly 50-2. Next in line going upward is
first plate 602 and second plate 640 for option assembly 50-1. Continuing
upward, first plate 602 is provided in RMIT 100 that is integrated into
IFD 2. At the top is the media edge reference base plate 680 found in IFD
2. The components just described are made from steel or other durable
material and may be chromed or plated to provide for enhanced resistance
to the wear caused by the media moving along media path P, media path
extensions PX, and media path branches PB.

[0146] Vertical media edge reference surfaces 604, 644 and 684 are
provided on first, second and base plates 602, 640, and 680,
respectively. Gap A is found between first and second plates 602, 640
within a given option assembly 50. Gap B is found between the top of
second plate 640 of one option assembly and the first plate of the
immediately superior RMIT 100. Gap C is found between the top of first
plate 602 in RMIT 100 of IFD 2 and the bottom edge of base plate 680. Gap
A is about 2.3 mm+/-0.4 mm. Gap B is about 2 mm+/-0.3 mm while Gap C is
about 2.3 mm+/-0.25 mm. The total vertical distance from the bottom edge
of first plate 602 in the bottom unit to the top of first plate 602 in
IFD 2 is approximately 330 mm with a total of only 6.6 mm in gaps.
Reference surfaces 604, 644, 684 form a substantially continuous surface
against which an edge of media being fed is biased against to ensure
alignment of media M as it travels along media path extensions PX and
media P path. Further each option assembly 50 has an overall height of
about 100 mm with the media reference surfaces 604, 644 forming a
substantially continuous reference surface save for gap A within option
assembly 50. Because of the relatively small size of gaps A-C, the chance
of media misalignment and media edge damage occurring as media
transitions from one reference surface to the next is significantly
diminished. Beveling 649 may also be provided on the bottom edges of
first, second and base plates 602, 640, and 680 which aids in the
transition of media as it is fed up the media extensions PX and media
path P. Beveling 649 is also provided on the front edges 646, 686 of
second and base plates 640, 680, respectively, and on rear edge 613 of
first plate 602. First plates 602 are vertically mounted on side portions
118A of front wall of RMITs 100.

[0147] As illustrated in FIGS. 39A, 39B, reference surfaces 604 of first
plates 602 extend in a first direction 606 the height H1 of side portion
118A and extend in a second direction 608 into media storage location
140. In one embodiment, the extension in second direction 608 is about 5
mm rearward of the back portion 116 of front wall 102. An edge of media
traveling through channel 126 or being fed from storage location 140
contacts and is aligned with reference surface 604. In one embodiment,
first plate 602 has first and second legs 610, 612 extending in first and
second directions 606, 608, respectively.

[0148] First plate 602 also may have a number of holes 616 for use with
fasteners that attach first plate 602 to side portion 118A of front wall
102. Further, a plurality of alignment holes 617 may also be provided
which receive corresponding posts or projections provided on side portion
118A which ensure that first plate 602 is properly aligned and oriented
on side portion 118. In the top edge of first plate 602, a notch 614 may
also be provided to accommodate drive shaft 511 of removable media dam
assembly 500 when it is installed in front wall 102. In addition to
providing a media edge reference surface, first plate 602 may also serve
as a support member for other components found in RMIT 100. For example,
feed roller 150, backup roller 152 and its carrier 161 may be mounted on
reference surface 604 via shaft 151, and posts 153, 159, respectively. On
outer surface 605 of first plate 602, intermediary gear 158 and drive
gear 160 are mounted on post 159 and shaft 151.

[0149] Referring again to FIG. 38, second plate 640 comprises a vertical
portion 641, a horizontal portion 643 extending outwardly from the second
plate and an alignment post 208F extending upwardly from horizontal
portion and spaced from vertical portion 641. Second plate 640 is mounted
atop side wall 204 and is aligned with front wall 102 of RMIT 100 when
installed in housing 200. The surface of vertical portion 641 that faces
toward RMIT 100 forms media reference surface 644 which surface may also
form an end of media slots 230, 232. Front and rear legs 645F, 645R may
extend upwardly from the top edge of vertical portion 641 to enclose an
end of media slots 230, 232. Use of front and rear legs 645F, 654R
extends the media reference surface 644 to be flush with a top surface of
top 202 of housing 200. Alignment features 647 (see FIG. 42) may be
provided on horizontal portion 643 for cooperation with corresponding
alignment features provided on top of side wall 204A for controlling
side-to-side and front-to-back positioning of second plate 640 atop of
side wall 204A. A top portion of post 208F is tapered to ease the
insertion of post 208F into opening 210 in the bottom of the superior
unit.

[0150] Base plate 680, in addition to having a plurality of media guides
690 extending outwardly from media reference surface 684, provides
support for various media feed rollers 692. As illustrated, 3 pairs of
media feed rollers 692 are shown.

[0151] Referring now to FIG. 40, there is shown a sectional view of side
wall 204A of housing 200 showing the internal structure of side wall 204A
and the relationship between second plate 640 of the inferior unit and
first plate 602 of the superior unit. For each option housing 200,
extending between opening 210 to beneath the intersection of horizontal
portion 643 with vertical portion 641 of second plate 640 is an internal
rib 227 extending to a top portion 205A of side wall 204A. In one
embodiment, because side wall 204A is molded, the distance D between the
outer surface 221 of interior portion 220 and the center of opening 210,
which is also the centerline of post 208F, may be tightly controlled.
Also, distance D represents the distance from the back surface of
vertical portion 641 to the centerline of post 208F. Further, the
distance from the center of opening 210 to the front of side wall 204A is
also closely controlled.

[0152] FIGS. 41 and 42 illustrate the aligning of first plate 602 with
second plate 640 of RMIT 100 during insertion of RMIT 100 into housing
200. Components and structures obscuring the view of second plate 640
mounting atop side wall 204A have been removed and second plate 640
appears to be floating in the air. As RMIT 100 closes, rear edge 613 of
first plate 602 approaches front edge 646. Both media reference surfaces
604, 644 are in the same vertical plane. In FIG. 42, RMIT is fully in
position in housing 200. First and second plates 602, 640 are aligned
with reference surface 604 enclosing the end of channel 126. FIG. 43
shows the alignment of first plate 602 with base plate 680 within IFD 2.
The RMIT 100 is fully in position within housing 20 of IFD 2.

[0153] Because of alignment features found in option assemblies 50-1, 50-2
and IFD 2, the horizontal misalignment between each of the units due to
tolerance stackup is between 0 mm and 0.25 mm or a total worst case
horizontal misalignment of 0.50 mm for the two option assemblies and IFD
2 shown. Whereas in prior art systems of having an image forming device
and two option assemblies, horizontal misalignment due to tolerance
stackup was about +/-2 mm. Such a reduction in horizontal misalignment
reduces skewing and jamming of fed media and improves the feed
reliability of this enhanced device.

System Schematic

[0154] A basic schematic of the various sensors and motors used to feed
media to IFD 2 is illustrated in FIG. 44. IFD 2 and with controller 3 is
shown on top of two option assemblies 50-1 and 50-2. Communications links
13 and 15 from controller 3 are connected to each option assembly 50-1
and 50-2 via electrical connectors 218 as previously described. Media
sensor 18 located in IFD 2 is shown connected to communications link 15,
which is shown providing input signals to controller 3 while
communications link 13 is shown providing output signals from controller
3. Communications links 13 and 15 may be one communications link. A media
sensor 18 is provided adjacent base plate 680 at the location shown as
arrow MS in FIG. 38. Also provided in IFD 2, are media sensor 240 for
sensing media in channel 126, media sensor 242 for sensing media picked
from RMIT 100, media out sensor 440 and index sensor 480, encoder wheel
sensor 492 and media size sensor 228. Connected to communication link 13
are feed motor 250 that drives feed roller 150 and separator roller 504
and the drive motor 404 used for the drive mechanism that powers pick
mechanism 300 and drives the lift arm and lift plate for indexing the
media into the picking location.

[0156] In option assembly 50-2, again connected to communications link 15,
are media sensor 240 for sensing media in channel 126, media sensor 242
for sensing media picked from RMIT 100, media out sensor 440 and index
sensor 480, encoder wheel sensor 492, media size sensor 228 and
controller 53. Like in option assembly 50-1, connected to communication
link 13, is controller 53 which in turn is connected to feed motor 250
that drives feed roller 150 and separator roller 504. However, provided
in option assembly 50-2 an alternate embodiment for the drive mechanism
400 is shown. Here two motors are provided in drive mechanism 400. Motor
404A is used to drive lift arm 173 to raise media M while motor 404B is
used to drive pick mechanism 400. By providing two motors 404A and 404B,
motor 404B can be run to move media counter to the media process
direction prior to each media picking operation without causing the
elevator lift arm 173 to move or index. The topmost media sheet is driven
back against the rear media restraint 170 which will assure the leading
edge of the topmost sheet of media will be located at a predetermined
distance with respect to the pick location. (See FIG. 45). In one
embodiment, the leading edge of media is about 10 mm downstream from the
pick location. This may be done prior to each media fed operation. With a
single motor in drive mechanism 400, the only time pick mechanism 300 is
rotating counter to the media process direction to provide alignment of
the leading edge of the topmost media sheet is when the elevator lift arm
is being driven to perform an indexing operation. During normal feeding
of media, pick mechanism 300 cannot be reversed prior to feeding each
topmost sheet without causing an index move to occur.

Methods for Media Feeding

[0157] For the methods described herein, reference is made FIGS. 45 and
46. As discussed above, lift plate 172 is raised in indexed moves. Motor
404 raises lift plate 172 until index flag 357 of pick mechanism 300
changes the state of index sensor 480. This signals that pick mechanism
300 has reached the lowest desired pick location. In one embodiment, lift
plate 172 continues to be raised a predetermined distance above the
lowest pick point as determined by motor 404 rotation. For example, lift
plate continues to raise approximately 2 mm, which is about the height of
20 sheets of 20 pound media. As media is fed, the pick mechanism moves
downward to a point just beneath the lowest desired pick point where the
index flags and changes the state of index sensor 480. This signals
controller 3, 53 to again index lift plate 172 upward to the
predetermined distance about the lowest desired pick point. For the
exemplary 2 mm index move just described, the rotation movement of pick
mechanism 300 is in an essentially linear motion, meaning that there is
only a minute variance in the pick location of the topmost sheet. Lift
plate 172 is raised periodically in an indexed move each time index flag
357 drops below index sensor 480. Thus media height positioning is
accomplished with use of a single sensor and the rotation of motor 404
while the media is still being fed by pick mechanism 300 without having
to wait for the trailing edge of the media to exit pick mechanism 300.

[0158] For example, assume that pick mechanism 400 had fed a media and has
been turned off as it has been engaged subsequently by downstream feed
rollers. Because of the light weight of pick mechanism 100, pick wheels
322 skid along the surface of the media being feed. At that point 712,
when pick mechanism 300 is turned off, there is still a trailing portion
of the media being fed that remains within the media storage location
140. The length of the trailing portion of the media remaining plus the
amount of interpage gap 720 for the next media to be fed translates in an
amount of time 730 available to perform an indexing move of lift plate
172. The amount of time is dependent on the process speed, the interpage
gap and the length of media being fed. As all three are known, controller
53 can determine if enough time is available to perform an index move.
Because with the present system, index moves are occurring in steps
ranging from approximately 1 mm to approximately 3 mm, indexing moves
take about 100 ms to occur and may be normally be performed on all
standard size media such as A4, etc. and even media as short as A6.

[0159] In prior art systems, an indexing sensor is located within the tray
within a few millimeters to the nominal location of the leading edge of
media to be fed and the leading edge of the media and the trailing edge
of the media being fed would have to be detected before an index move of
a lift plate could occur. However, at this location, a reliable signal
from the indexing sensor was difficult to achieve while media was moving
past the indexing sensor. When the trailing edge of the media being fed
cleared the indexing sensor, the indexing sensor could be reliably read.
Thus, indexing move could not be initiated until the media being fed had
exited the tray. This increases the interpage gap between successively
fed media, as much as 250 mm in some prior art designs, decreasing
throughput.

[0160] Further in prior art designs, the downward rotation movement of the
pick mechanism into the media tray can result in the pick location moving
as much as 60 mm leading to a high amount of uncertainty in the location
of the leading edge of the media being feed. To account for this leading
edge uncertainty, additional media edge sensors for sensing leading and
trailing edges were suspended into the media storage location.

[0161] A method for determining the amount of media remaining in RMIT 100
is also provided. Lift plate 172 supporting a stack of media is raised
toward pick mechanism 300 for feeding the media sheets by rotation of
motor 404. As discussed above, where a single motor 404 is used to raise
lift plate 172 and drive pick mechanism 300, lift plate 172 is raised
when motor 404 rotates pick mechanism 300 opposite the media process
direction. Conversely, when motor 404 drives pick mechanism 300 in the
media process direction, lift plate 172 is held in place. Each time lift
plate 172 is raised or indexed, controller 3, 53 determines an amount of
rotation of motor 404 and stores this value in memory 8. The amount of
rotation of motor 404 can be determined by counting the number of pulses
of encoder wheel 490 as motor 404 rotates. Each time RMIT 100 is removed
from housing 20, lift plate 172 falls to bottom 108 of RMIT 100. When
RMIT 100 is re-inserted into housing 20, lift plate 172 is then raised
from bottom surface 108 until index sensor 357 changes the state of index
sensor 480. As a result, embodiments include those wherein each time RMIT
100 is removed from housing 20, the determined amount of rotation of
motor 404 is reset. Because lift plate 172 is raised from bottom 108 of
RMIT 100 each time RMIT 100 is removed and re-inserted into housing 20
when RMIT 100 is relatively empty, motor 404 must rotate a number of
times in order to raise lift plate 172 to desired pick height. In
contrast, when the RMIT 100 is relative full, relatively few rotations
are necessary to raise lift plate 172 to the desired pick height.
Accordingly, by tracking the number of rotations of motor 404 in the
direction of rotation used to raise lift plate 172, controller 3, 53 is
able to estimate the amount of media remaining in RMIT 100.

[0162] IFD 2 provides an indication of an amount of media sheets remaining
in each RMIT 100 based on the determined amount of rotation of its
respective motor 404 used to raise lift plate 172. In some embodiments,
when the number of rotations of motor 404 exceeds a predetermined
threshold, IFD 2 signals that the amount of media sheets remaining in
RMIT 100 is low. Alternatives include those wherein IFD 2 displays an
estimate of the amount of media sheets remaining in RMIT 100 in the form
of a "gas gage." Embodiments include those wherein IFD 2 then signals
that RMIT 100 is empty when flag arm 442 falls through opening 176 in
lift plate 172. The signal or gas gage may be provided on display 34.
Alternatively, the tray low or tray empty status may be displayed on an
indicator light such as an LED indicator light. Alternatives include
those wherein the signal or gas gage is provided on a display device of a
peripheral unit such as a computer 16 connected to IFD 2 either directly
or indirectly via a communications link

[0163] An issue arises when RMIT 100 is removed when IFD 2 is turned off.
If this occurs, the amount of rotation of motor 404 stored in memory 8
may no longer be indicative of the amount of media remaining in RMIT 100
as a result of the removal of RMIT 100. First, removal of RMIT 100 causes
lift plate 172 to fall to the bottom 108. Second, media may have been
added to or subtracted from RMIT 100 when it was removed. The amount of
rotation of motor 404 stored in memory 8 will not take into account the
change in position of lift plate 172 or the added or subtracted media.
When IFD 2 is turned on, controller 3, 53 determines whether lift plate
172 needs to be raised based on the status of index sensor 480. When lift
plate 172 needs to be raised when the power is turned on, in order to
correct the amount of rotation of motor 404 stored in memory 8,
controller 3, 53 determines whether the number of rotations of motor 404
required to raise lift plate 172 exceeds a predetermined amount of
rotation associated with a nominal index. If it does, this indicates that
RMIT 100 was removed while IFD 2 was turned off and controller 3, 53
resets the amount of rotation of motor 404 stored in memory 8 as of the
beginning of the index operation. This helps ensure that the amount of
rotation of motor 404 stored in memory 8 reflects the current status of
the media remaining in RMIT 100.

[0164] While the present example embodiment of a method for determining
the amount of media remaining in RMIT 100 discusses the use of a single
motor 404 to raise lift plate 172 and drive pick mechanism 300, it will
be appreciated that the method is equally applicable in embodiments
wherein separate motors 404A raise lift plate 172 and motor 404B drive
pick mechanism 300, respectively. In such embodiments, controller 3, 53
tracks the number of rotations of motor 404A in the direction that raises
the lift plate 172. The number of motor rotations is then used to provide
an indication of the amount of media remaining in RMIT 100.

[0165] Referring to FIG. 45, a method for positioning and feeding media
into a media feed path is also provided. Pick mechanism 300 is driven in
the media process direction to move a first or topmost media sheet 702
from the top of the stack of media sheets in media storage location 140
in the media process direction from an initial pick position 710 into the
media feed path P, media path extension PX or media path branch PB
leaving a second media sheet 704 at the top of the stack of media sheets.
Leading edge 702L of topmost media sheet 702 moves tangentially over and
atop separator rollers 504 that rotate opposite the media process
direction. While trailing edge 702T has not exited from beneath pick
wheels 322, topmost sheet 702 is being bent to conform to the angle of
the media dam contact surface 502 as it is fed by pick mechanism 300.
This applies a normal force against separator rollers 504 and the lower
surface of topmost sheet 702 acts as a nip with respect to a following
sheet that is double fed or shingle fed with the topmost sheet. If
topmost and following media sheets 702, 704 are double fed or shingle
fed, leading edge 704L of the following media sheet 704 strikes separator
rollers 504 in a non-tangential direction and the rotation of separator
rollers 504 counter to the process direction together with the nip force
applied by topmost sheet 702 skives off and stops further motion of
following media sheet 704 in the media process direction at about
separation point 701 immediately upstream and adjacent separator rollers
504. Skiving of following sheet 704 is achieved in part due to the
reactionary force received from separator rollers 504 and applied to
following sheet 704. The leading edge of the media sheet refers to the
edge of the media sheet closest to the entrance to media path P, media
path extension PX or media path branch PB. Double feeding refers to a
condition when both the topmost and following sheets are fed together
with their leading edges substantially aligned. Shingle feeding refers to
a condition where the topmost and following sheets are fed together, but
the leading edge of the following sheet is upstream of or lags behind
leading edge 702L of topmost sheet 702 usually about 1-5 mm up to the
length of the page. After topmost media sheet 702 is fed, if following
media sheet 704 was double or shingled fed with topmost media sheet 702,
leading edge 704L of following media sheet 704 may be at separation point
701 on media dam 500 directly upstream and adjacent to separator rollers
504. If following media sheet 704 was not shingled fed, it will be
positioned such that the pick position for it will be pick position 710.
It is also possible that the following media sheet may have been
partially shingled fed such that its leading edge is located somewhere
between initial pick position 710 and separation point 701 after topmost
media sheet 702 is fed. In some embodiments, this distance may range from
6-10 mm. As illustrated, the distance between separation point 701 and
pick position 710 is about 20 mm and this would be the maximum amount of
uncertainty 700 in the location of the leading edges. As illustrated, the
distance D1 between pick wheels 322 and separator rollers 504 is about 10
mm.

[0166] In media storage location 140, pick mechanism 300 is then driven
opposite the media process direction, to move following media sheet 704,
opposite the media process direction away from the entrance to the media
feed path until leading edge 704L of following media sheet 704 reaches a
known predetermined position in the media storage location thereby
reducing uncertainty regarding the location of the leading edge. In some
embodiments, following media sheet 704 is moved opposite the media
process direction until trailing edge 704T of the sheet contacts rear
media restraint 170 thereby positioning leading edge 704L and pick
position 710 at known locations. In those embodiments that do not include
a rear media restraint 170, following media sheet 704 may be moved
opposite the media process direction until trailing edge 704T contacts
the rear wall 106. Embodiments include those wherein pick mechanism 300
is driven opposite the media process direction for a set amount of time
such that, in some cases, after the trailing edge of the media sheet
contacts rear media restraint 170 or rear wall 106, pick mechanism 300
continues to rotate opposite the media process direction. However, the
weight of pick mechanism 300 is low enough that the normal force applied
by pick mechanism 300 is small enough to allow pick wheels 322 to slip
against the surface of the media sheet. This aids in preventing pick
mechanism 300 from wrinkling or bending the media sheet by excessively
forcing it against rear media restraint 170 or rear wall 106. After
leading edge 704L of the following media sheet 704 reaches the known
predetermined position, pick mechanism 300 is driven in the media process
direction to move following media sheet 704 in the media process
direction from the stack of media sheets M into media feed path P, media
path extension PX or media path branch PB.

[0167] In addition to reducing leading edge uncertainty 700 by moving
leading edge 704L of following media sheet 704 to a known location,
rotation of pick mechanism 300 opposite the media process direction prior
to feeding following sheet 704 helps eliminate leading edge uncertainty
that occurs as a result of backlash in drive transmission 304 and drive
transmission 401. When pick mechanism 300 is driven opposite the media
process direction, each of the gears in respective drive transmissions
304, 401 are moved all the way to one end. At this point, the total
backlash in the system is known and can be accounted for. This
substantially eliminates the leading edge uncertainty that occurs as a
result of drive transmission backlash. Leading edge uncertainty 700 is
further reduced through the use of lift plate 172 which limits the pick
height to a discrete rotational range of pick mechanism 300. In normal
operation for the illustrated systems, media is indexed in about 2 mm
increments, meaning the pick mechanism 300 rotates through about 2.5
degrees of rotation. This, in turn, limits the leading edge uncertainty
that occurs as a result of change in the distance from the initial pick
position due to such rotation. By reducing leading edge uncertainty,
interpage gap 720 between successive media sheets can be reduced. In
turn, IFD 2 is able to feed media at a higher rate of speed with the same
linear velocity of each page. In those embodiments where IFD 2 includes
an image transfer section, reduced leading edge uncertainty also aids in
image transfer, as precise knowledge of the position of the media sheet
is necessary in order to accurately place an image on a media sheet.

[0168] In those embodiments that include a common motor 404 for driving
pick mechanism 300 and raising lift plate 172, media is moved opposite
the media process direction when lift plate 172 is raised as a result of
index flag 357 changing the state of index sensor 480. Alternative
embodiments include those wherein pick mechanism 300 and lift plate 172
are driven by separate motors and those wherein no lift plate 172 is
included such that pick mechanism 300 gradually descends as media is fed
from RMIT 100 in order to remain in contact with the topmost media sheet.
In these embodiments, pick mechanism 300 may be driven opposite the media
process direction after each pick in order to move the next media sheet
opposite the media process direction until its leading edge reaches a
known predetermined location and a known pick location.

[0169] A further media feeding method is also provided. The method
provides for varying the separation force depending upon the weight of
the media experiencing misfeed problems. Referring to FIG. 46, shown are
four curves 802, 804, 806, and 820 indicating the relationship between
the distance in millimeters from the top of the media stack to the
separation point at separator rollers 504 (along the X axis) and the
force in grams (along the Y axis). The distance measurement is
essentially a vertical measurement taken from the top of the media stack
on elevator lift plate 172. All four curves exhibit the same general
shape in that as distance from the top of the media stack to the
separation point decreases, sheet separation force increases in a
non-linear manner. Curves 802, 804, and 806 increase in an asymptotic
manner as the distance decreases. Curve 802 shows the amount of force
provided by pick mechanism 300. Curves 804 and 806 show the maximum and
minimum reactionary separation forces provided by separator rollers 504.
Two separation force curves are provided to account for component
variance in separator rollers, media contact surfaces, etc. Curves 802,
806 and 806 were developed using 20 mm diameter pick wheels 322, 20 pound
paper as the media, and a media contact surface 502 that forms a 125
degree angle with respect to bottom 108 of RMIT 100 (conversely media
contact surface 502 can be said to form a 55 degree angle with respect to
the top of rear portion 116 of front wall 102). It will be realized, that
in order to reliably separate double fed and shingle fed media, the
separation force needs to be greater than the pick mechanism feed force
over the chosen indexing range and the operating range. Operating areas
810, 812 are chosen, usually by testing, to provide sufficient force for
feeding media and separating media of different types over all indexing
ranges without having forces of an upper magnitude that could damage
media while also have forces of a lower magnitude that can still feed and
separate media. For the illustrated curves, it was empirically determined
that the maximum distance from the top of the media stack to the
separation point distance would be about 13 mm (a lower extent of the
range) and still have enough force for reliably feeding and separating
media and conversely, the minimum distance from the top of the media
stack to the separation point distance was chosen to be about 6 mm (an
upper extent of the range) to limit the force so as to prevent damage to
the media.

[0170] Within the lift plate indexing normal range 830, chosen to be from
between a normal upper extent at about 10 mm to a normal lower extent at
about 12 mm, distance between the top of the media stack to the
separation point along curve 804, the maximum separation force varies in
a substantially linear fashion from about 390 grams to about 250 grams,
along curve 806, the minimum separation force varies in a substantially
linear fashion from 550 grams to about 390 grams, and along curve 802,
the pick force varies in a substantially linear fashion from about 250
grams to about 200 grams. This is designated normal operating area 810.
Similarly, within the lift plate indexing extended range 832, chosen to
be from between an extended upper extent at about 6 mm to an extended
lower extent at about 13 mm distance from the top of the media stack to
the separator point, the minimum separation force along curve 804 varies
in a nonlinear fashion from about 650 grams to about 250 grams, along
curve 806, the maximum separation force varies in a nonlinear fashion
from 980 grams to about 380 grams, and along curve 802, the pick force
varies in a nonlinear fashion from about 550 grams to about 200 grams.
This is designated extended operating space 812. Other normal and
extended operating areas 810, 812 may be used.

[0171] When feeding media, if double feeds or shingle feeds occur with
heavier weight media, separation forces will be increased by indexing
elevator lift plate 172 upward. As previously described, index sensor 480
is provided, which changes state due to motion of index flag 357 on pick
mechanism 300. Because elevator lift plate 172 is indexed only in one
direction, upward, index sensor 480 is positioned at a predetermined
point P1 that is either at or beyond the lower extent of the extended
operating range 812. For example, P1 may be located at a point where the
top of the media stack would be 15 mm from the separation point. It is at
this point P1 where further rotation of motor 404 to raise lift plate 172
is tracked. As the elevator lift plate 172 is raised from the bottom 108
of RMIT 100, pick mechanism 300 will eventually come into contact with
the top of the media stack and will be raised, along with the media
stack, to the predetermined point P1 at which index flag 357 actuates
sensor 480. From this point P1, the lower extent in the lift plate
indexing extended range 832 and extended operating area 812 can be
established by tracking motor 404 rotation or point P1 may be used to set
such lower extent of lift plate indexing extended range 812. For normal
operation, continued rotation of motor 404 beyond point P1 is measured
until the 12 mm distance from the top of the media stack to the
separation point is achieved setting the lower normal extent in the lift
plate indexing normal range 830 and operating area 810. A subsequent 2 mm
normal index move to reach the 10 mm distance reaching the upper extent
of normal operating area 810 is made. During normal media feeding and
indexing operations, as media is fed, the distance from the top of the
media stack to the separation point varies between 10 mm to 12 mm, at
which an index move raises the top of the media stack to 10 mm from the
separation point.

[0172] In order to achieve a lower than normal separation force for
lighter weight media, feeding of the lighter weight media would occur
when the distance from the top of the media stack to the separation point
was at, for instance, 13 mm rather than 12 mm. Separation forces are
decreased by resetting the elevator lift plate by pulling RMIT 100
outwardly from its housing 20, 200, reinserting it and then indexing
elevator lift plate 172 up until the top of the media stack reaches point
P1 at which media sensor 480 changes state. To achieve a higher than
normal separation force, resetting the elevator lift plate is not
required, indexing of elevator lift plate 172 would continue until the
distance from the top of the media stack to the separation point was at a
predetermined point P2 between about 6 mm and about 10 mm.

[0173] Accordingly, in some embodiments, media position is adjusted based
on media type. Controller 3, 53 first determines the type of media on
lift plate 172. The media type may be indicated by a user, for example,
at user interface 7 or at a peripheral device. Alternatives include those
wherein the controller 3, 53 determines the media type based on the
position of actuators 142. When the media is a first media type that does
not require adjustment of the separation force outside of the normal
range 830, indexing is performed as described above. Motor 404 is driven
in a first direction to drive pick mechanism 300 for feeding the media in
the media process direction such that as media is fed, the height of pick
mechanism 300 decreases. Between each pick, the controller 3, 53
determines if the height of the pick mechanism has fallen below
predetermined level, for example by determining whether index flag 357
has changed the state of index sensor 480. When the height of pick
mechanism 300 falls below the predetermined level, motor 404 is driven a
first predetermined amount of rotation in a second direction, opposite
the first direction, to raise lift plate 172 to raise pick mechanism 300
to a first desired pick height. As discussed above, in some embodiments,
motor 404 raises lift plate 172 until the increase in height of pick
mechanism 300 changes the state of index sensor 480 and then motor 404
rotates the first predetermined amount of rotation. In other embodiments,
indexing is performed solely based on encoder 490 pulses. Once index flag
357 drops below index flag 480 thereby indicating that an index is
required, motor 404 rotates the first predetermined amount of rotation
without regard to when index flag 357 changes the state of index sensor
480 as a result of the increase in height of lift plate 172.

[0174] Conversely, when the media is second type that requires increased
or decreased separation force outside of the normal range 830, a modified
index operation is performed. Motor 404 is driven in a first direction to
drive pick mechanism 300 for feeding the media in the media process
direction such that, as media is fed, the height of pick mechanism 300
decreases. Rather than analyzing whether index flag 357 has changed the
state of index sensor 480, controller 3, 53 determines the amount of
media fed since the last index, for example, by counting the number of
media fed or by determining an amount of rotation of motor 404 in the
first direction. Once the number of media exceeds a predetermined
threshold indicating that pick mechanism 300 has reached or is about to
reach the minimum pick height, motor 404 is driven a second predetermined
amount of rotation in the second direction to raise lift plate 172 to
raise pick mechanism 300 to a second desired pick height different from
the first desired pick height. If the second desired pick height is above
the first desired pick height, then (1) the distance from the second
desired pick height to the separation point is less than the distance
from the first desired pick height to the separation point and (2) a
reaction force applied by separator rollers 504 to a media sheet fed from
the second desired pick height is greater than the reaction force applied
by separator rollers 504 to a media sheet fed from the first desired pick
height. In contrast, if the second desired pick height is below the first
desired pick height, then (1) the distance from the second desired pick
height to the separation point is less than the distance from the first
desired pick height to the separation point and (2) the reaction force
applied by separator rollers 504 to a media sheet fed from the second
desired pick height is less than the reaction force applied by separator
rollers 504 to a media sheet fed from the first desired pick height.
Accordingly, it will be appreciated that the separation force can be
modified by altering the timing and amount of indexing that is performed
depending on media type.

[0175] The foregoing description of several methods and an embodiment of
the present disclosure have been presented for purposes of illustration.
It is not intended to be exhaustive or to limit the present disclosure to
the precise steps and/or forms disclosed, and obviously many
modifications and variations are possible in light of the above
description. It is intended that the scope of the present disclosure be
defined by the claims appended hereto.